BPG Parchment Historic Treatment Methods and Materials

From Wiki

Book and Paper Group Wiki > Paper Conservation Wiki > Parchment Historic Treatment Methods and Materials

This page covers outdated and historic parchment treatments. See also: Parchment, Parchment Examination and Documentation, Parchment Condition Problems, Parchment Conservation Treatment, and Parchment Housing and Storage.

Wiki Compiler: Cathie Magee
Wiki Contributors: your name could be here

Copyright 2023. The Book and Paper Group Wiki is a publication of the Book and Paper Group of the American Institute for Conservation. It is published as a convenience for the members of the Book and Paper Group. Publication does not endorse nor recommend any treatments, methods, or techniques described herein. Information on researching with the wiki and citing the BPG Wiki can be found on the Reference and Bibliography Protocols page. The BPG Wiki coordinators can be reached at bookandpapergroup.wiki@gmail.com.

Cite this page:

BPG Parchment Historic Treatment Methods and Materials. 2023. Book and Paper Group Wiki. American Institute for Conservation (AIC). Accessed March 29, 2023. https://www.conservation-wiki.com/wiki/BPG_Parchment_Historic_Treatment_Methods_and_Materials


This content has been copied from the original BPG Parchment wiki page.

Historic Treatment Techniques[edit | edit source]

[Copied from original BPG Parchment page]

[Not all of what was copied is relevant. -CM]

Adhesives and Consolidants[edit | edit source]

(for a more complete discussion of many of the following materials see Consolidation, Fixing, and Facing and Adhesives.)

Collagen-based Adhesives

  • Animal Hide Glue
General Information: Hide glue was used heavily in the past, starting around the 16th century, for the repair of parchment manuscripts, documents, and other artifacts and for rebinding parchment codices. (See Cleaning Methods.) Hide glue continues to be used today in some countries (particularly the United Kingdom) for gluing up the spines of books after sewing and for other steps in the bookbinding process.
Preparation: Hide glue is prepared by soaking and then cooking in water a variety of animal waste products (usually from cows) such as skin, hooves and horns. The strained solution, which is usually caramel brown in color, can be used as is or dried into sheets or pellets. In order to remain liquid during use the adhesive must be kept warm in a double boiler. In the U.K. commercially made hide glue is often referred to as “Scotch Glue”.
Caveats: Since hide glue is not as pure as other collagen-based adhesives such as gelatin and parchment size it is not currently recommended for use in conservation.
  • Parchment Size
General Information: Parchment size is used both as an adhesive and as a consolidant. It has a long history of use by artists and craftspeople and recipes are found in many early artists' treatises such as those written by Cennino Cennini and others.
Preparation: Parchment size is made from small pieces of new parchment that are soaked overnight in distilled or deionized water and then cooked in a double boiler at approximately 50°C for about 6–8 hours, and sometimes longer. (Water may need to be added to the solution during cooking in order to counteract the effects of evaporation.) The adhesive is decanted (sometimes strained through cheese cloth) and allowed to cool until it forms a gel. (Wächter 1982, p.164.) In some recipes the water used to soak the parchment clippings is discarded and fresh water is added for the cooking stage. (Giuffrida 1983, p.41.) This sometimes makes a weaker adhesive than when the soak water is also used for cooking.
Use: Parchment size is applied with a brush or, when sufficiently diluted, with a spray gun or an air brush. In some workshops ethanol or isopropanol is added to the solution in order to achieve better penetration during consolidation. If the parchment size is very viscous when the alcohol is added the solution will coagulate. It is important, therefore, to dilute the adhesive with water first before adding any alcohol. Alternatively, alcohol can be applied either by brush or spray gun in a separate step, prior to the application of the consolidant. The temperature of the parchment size also may be a factor in determining the amount of alcohol that can be added to the parchment size, and/ or can affect the interaction of the parchment size with the parchment and/ or pigments. Solutions of parchment size must be kept warm in a double boiler during use, in order to keep them liquid. Additives such as wine vinegar (which, when added in sufficient quantity, prevent the solution from forming a gel at room temperature) and alcohol (which aids in penetration of the media and support) have been recommended by some authors. (Reed 1972, pp.223–224, Wächter 1982, p.164.) Other materials such as flour paste, gum arabic, honey and glycerin have been added to parchment size in the past, largely in an effort to increase the flexibility of the adhesive film once dried. (Reed 1972, pp.223–224.) However the use of these additives is now discouraged because of concern about their effect on the media and the support, and the possibility of future microbial attack (See Consolidation of Media and Mending and Filling.)
Storage: If kept in the refrigerator parchment size has a limited shelf-life. For long-term storage the liquid adhesive can be poured into thin sheets and then dried, or it can be frozen in small ice cube trays. Each time the parchment size is heated in order to make it liquid, the relative strength of the solution should be tested. Water can also evaporate during use so the viscosity of the solution may change dramatically over a period of several hours.
Caveats:
  • Since a variety of chemicals are currently used in the production of parchment the conservator can never be sure of the purity of a solution that derives from modern skins. Therefore, for certain applications, it may be wiser to choose gelatin instead of parchment size if a collagen-based adhesive is desired. Parchment size is attractive to insects and mold, in conditions of high relative humidity, and it will also become brittle under excessively dry conditions. Protein films shrink upon drying. It is degraded by ultra-violet light and yellows with age. The strength of parchment size may not always be desirable, and it can sometimes be too glossy when applied as a consolidant to very matte paint surfaces. When used in a thin, warmed solution both parchment size and gelatin will tend to penetrate the parchment skin, thus making them difficult to reverse at a later date.
  • Many modern parchments have been treated with formaldehyde by the manufacturer to minimize moisture reactivity, and will therefore be useless in size preparation. (PY)
  • Parchment size is more alkaline than gelatin due to the presence of residual lime and/ or chalk in the skin. This should be taken into consideration when using parchment size for the consolidation of pH-sensitive colorants.
  • Gelatin
General Information: Gelatin is used both as an adhesive and a consolidant for the conservation of parchment. Food grade gelatin is available commercially in sheet form (known as edible leaf gelatin) and also in powdered or granulated form. More highly purified pharmaceutical grade and “photographic quality” gelatins are available in granulated form from Eastman Kodak and Fisher Scientific. Gelatins are graded by viscosity in millipoises and jelly value in Bloom grams. The lower the Bloom number, the weaker the gel. (See Adhesives: Proteinaceous Adhesives: Collagens: General Information: Chemical and Physical Properties) Solutions of gelatin are quick to prepare and the actual concentration of gelatin in solution is easily documented. For these reasons gelatin is often preferred over parchment size by many conservators.
Preparation: Leaf, powdered or granulated gelatin are all prepared in a similar way by swelling the adhesive in cold water for an hour or more, and then heating it at approximately 50°C until it goes into solution. In the past, painters and restorers have used such additives as common salt, urine, calcium chloride, zinc chloride, magnesium chloride, herring brine, etc., to alter the hardening (i.e., resulting flexibility) of gelatin (see Wehlte 1975, p.374).
Use: Gelatin must be kept warm in a double boiler so that it stays liquid during use. It can be applied directly with a brush or used in a dilute form in a spray gun or air brush. In the past Anthony Cains has included additives such as sorbitol (a humectant which, in theory, keeps the adhesive flexible upon drying) and small quantities of dilute acetic acid to gelatin when it was used as an adhesive (Cains 1982/83, p.22.) However, this practice has long been discontinued by Cains because the additives seemed to have little effect; controlling the film thickness of the adhesive produced better results. (AC) In order to achieve greater penetration during consolidation treatments it is common to add either ethanol or isopropanol directly to a dilute solution of gelatin or to apply the alcohol in a separate step to the area being consolidated.
Storage: Refrigeration will prolong the shelf life of a gelatin solution for approximately one month. For long-term storage liquid gelatin can be dried or frozen (see description of parchment size above), yet this is rarely done because fresh solutions are easily prepared from the commercial product.
Caveats: Similar to those associated with parchment size. Gelatin solutions can often be more yellow in color yet they possess a similar tack to solutions of parchment size. Gelatin solutions will tend to be more acidic (pH 4–5) and even more so if acetic acid is added.
  • Sturgeon Glue (Isinglass)
General Information: Sturgeon glue has a long history of use in Eastern Europe as a consolidant and an adhesive in both painting and paper conservation. In contrast to fish glue, which is made from the head, skin and bones of fish, isinglass is prepared from the inner membrane of the air or swim bladder of the sturgeon. Russian isinglass, prepared from two specific types of sturgeon, is considered to be the superior product compared to other types of isinglass. (See discussion of types of fish used to manufacture “Russian Isinglass”, Alexander.) Sturgeon glue is also said to have a lower viscosity and greater tack than other collagen-based adhesives (see discussion of surface tension in Bogue 1922, p.115), such as gelatin or parchment size, and its lower gelation temperature is also advantageous in certain situations when high heat cannot be employed. Certain varieties of isinglass (yet not the Russian type) are sold by Kremer Pigments in New York and Germany and by Cornellisen in London.
Preparation: According to Petukhova and Bonadies (1993, p.23) “Sturgeon glue is made by washing the fish bladders in hot water to remove extraneous material. The bladders are then cut open to expose the inner membrane to the air. When almost dry, the outer membrane is removed by rubbing and beating.” The dried inner membrane, which is usually sold in either thick sheets or as thin, narrow strips, is allowed to soak and swell in water for several hours. The water is decanted and fresh water is added to the swollen glue in a double boiler. The glue is gently cooked at a low temperature (no greater than 60°C) until the membrane dissolves. The solution is strained if necessary prior to use.
Use: Although information about the use of isinglass for the conservation of parchment artifacts is not readily available, it has been recently suggested as a possible consolidant for flaking paint on parchment supports. (See Petukova and Bonadies 1993, p.29.) Since isinglass will gel upon cooling it needs to be kept warm in a double boiler during use. It is most often applied with a brush, yet can also be used in spray form for consolidation purposes. A repair tissue coated with isinglass (the manufacture of which is described by Petukhova 1989) has been recently used for semi-transparent mends on parchment (see Mending and Filling). Honey has traditionally been added to solutions of isinglass for use in painting conservation, and other plasticizers such as glycerin and propylene glycol have been suggested as possible substitutes. However, the long-tern effects of these additives have not yet been thoroughly investigated. (See Petukhova and Bonadies 1993, p.24.)
Storage: The stock solution of isinglass can be kept for several days if refrigerated. For long-term storage solutions of isinglass can presumably be dried or frozen, but this is usually unnecessary since the adhesive is easily prepared from the dried commercial product.
Caveats: The purest type of isinglass is manufactured in the former Soviet Republic and is therefore difficult to obtain in the West. It is very hygroscopic and even more so for products made from insufficiently washed raw materials that contain much sodium chloride. Sturgeon glue is also susceptible to attack by insects and mold in conditions of high relative humidity. It can also become brittle under very dry storage conditions.

Vegetable Adhesives

  • Flour Paste
General Information: Flours are made by grinding and sifting the meal of a grain, especially wheat. Although flours are made up primarily of starch, a naturally occurring polymer of glucose, they also contain brown chaff and other particles that affect the color and texture of an adhesive made from flour. Due to the low cost and easy availability of this material, among other factors, pastes made from wheat flour have been in use for centuries.
Preparation: Wheat flour is dissolved in water to make a slurry and then cooked at a moderate temperature, often in a double boiler, with constant stirring. Once cool the paste may or may not be strained, and it is then diluted with water for use.
Use: A mixture of 50/50 boiled flour paste and hide glue (“Technical Skin Gelatin”), which also contained small quantities of alum and thymol, was used for the repair of the Book of Kells in the 1950s. Flour paste has also been suggested as one of many possible additives to parchment size when used for the repair of parchment artifacts (Reed 1972, p.223). In some countries flour paste continues to be used on its own as an adhesive for repair work, and also for a particular method of tension drying on Plexiglas which is practiced largely in the United Kingdom. (See Flattening/Tensioning/Drying). Wheat flour paste, buffered to a neutral pH with magnesium hydroxide, was recently selectedä over other adhesives for the repair of the 11th c. English Doomsday Book. (See Forde 1986, pp.36–37.)
Caveats: Flour pastes are not considered to be as pure as wheat or rice starch pastes and are therefore not currently recommended for use in conservation. Also, due to the complex make-up of flour, aged films can be very difficult to reverse with water alone.
  • Starch Paste
General Information: In parchment conservation wheat and rice starch pastes have been used primarily as adhesives; they are generally considered too viscous for use in consolidation. (See Mending and Filling.) Starches derive from a variety of plant sources including corn, potatoes, rice and wheat, yet all are polysaccharides that are made up of two basic components: amylose and amylo-pectin. Wheat starch generally has a higher percentage of amylose (17–27%) than rice starch.
Preparation: Many recipes for the preparation of rice or wheat starch paste have been published in the conservation literature. In general the dry powder is soaked in water and then cooked at a moderate temperature with constant stirring. During the cooking process the granules of amylose and amylopectin swell and burst, forming a sticky paste. After cooking the paste is strained and then diluted with water for use. Wheat and rice starch are currently available from many conservation suppliers including Talas, Conservation Materials, University Products and others.
Use:
  • Wheat starch paste is currently used with Japanese paper and also with new parchment for the repair of damaged parchment manuscripts and documents. It can also be used with goldbeater's skin or fish skin yet the mend is not often as strong or transparent as when gelatin or parchment size are employed. In a recent series of tests on a variety of adhesives being evaluated for use in parchment repair wheat starch paste performed very well (see Wouters et. al., 1992).
  • Rice starch paste is generally considered to produce a smoother and stronger but more brittle adhesive than wheat starch paste (See Adhesives: Rice Starch Paste). Although not as widely used for repair as wheat starch paste, rice starch tends to be preferred by many book conservators for certain specific applications.
Caveats: Starch films shrink upon drying and can continue to lose moisture and shrink over time, especially in conditions of low relative humidity. Starch films do not seem to adhere well to a smooth surfaced parchment. Aged starch films can sometimes be difficult to reverse, although this presents a greater problem when applied to a weak degraded parchment than a healthy one.
  • Vegetable Gums
Vegetable gums such as gum arabic have been suggested in the past as possible additives to parchment size when it is used as an adhesive for the repair of parchment. (See Reed 1972, pp.223–224.) Gum arabic is not currently recommended for this purpose, however, because of the increased risk of microbial attack. Despite the fact that gum arabic has historically been used as a binder for painting on parchment it has been observed to curl and peel dramatically when dry. (HS) For this and other reasons the use of gum arabic as a consolidant for flaking media on parchment is not currently recommended.
  • Cellulose Ethers
General Information: Cellulose ethers are made from wood pulp or cotton linters that are swollen and decrystallized using sodium hydroxide. The “alkali” cellulose undergoes etherification or methylation in order to partially substitute the hydroxyl groups on the anhydroglucose ring with alkyl or hydroxyalkyl groups such as methyl, ethyl, sodium carboxymethyl, hydroxyethyl or hydroxypropyl. After neutralization with acids the cellulose ether is further purified and then dried, milled and sifted. Cellulose ethers are produced by many companies in various grades, viscosities and degrees of polymerization (DP). The best products are the highly purified varieties made for adhesive applications.
Preparation: Most cellulose ethers are soluble in cold water. Sodium carboxymethyl cellulose and hydroxyethyl cellulose are also soluble in hot water. Only hydroxy-propyl, ethyl hydroxyethyl cellulose, and ethyl cellulose are initially soluble in polar organic solvents. Although clumping usually occurs upon adding the dry powder to the solvent the cellulose ether eventually goes into solution, especially if stirred regularly.
Use: Cellulose ethers are generally not strong enough to be used on their own as adhesives for the repair of healthy parchment, but they often work well for the consolidation of friable or flaking media and for the consolidation and repair of weak or degraded parchment. In these situations the adhesive is usually applied with a brush. Cellulose ethers can also be mixed with other adhesives, to alter or improve their working characteristics.
  • Methyl Cellulose: Methyl cellulose is produced by several American and European companies under different trade names. Dow Chemical produces Methocel; Culminal, produced by Henkel in Germany, is sold in the U.S. by Process Materials or Archivart who attaches their own name to the product. A roughly 1–2% solution of methyl cellulose in water and ethanol is sometimes used as a consolidant for powdery matte paint in illuminated manuscripts (A.Q.). A methyl cellulose with a high degree of polymerization, dissolved in 80/20 methylene chloride/ methanol, has been used for ink consolidation on parchment in Italy. (See Consolidation of Media.)
  • Hydroxypropyl cellulose: This cellulose ether is manufactured by the U.S.-based Hercules Corporation who labels their product Klucel. A 2–5% solution of Klucel-G in ethanol is used by Anthony Cains for the local sizing of degraded parchment prior to repair. (See Consolidation of Degraded Parchment.) Klucel-G in ethanol is also used for media consolidation on parchment in several European countries. (See Consolidation of Media.) Repair tissues coated with more viscous solutions of Klucel-G or Klucel-J in ethanol have recently been used for the repair of weak, degraded parchment. (See Mending and Filling.)
  • Methyl hydroxyethyl cellulose: This cellulose ether is made by Hoechst in Germany under the trade name of Tylose. It is widely used in Europe for both paper and parchment conservation. Tylose MH300 is currently used in Italy, either on its own or mixed with 5% Vinavil, a polyvinyl acetate emulsion, for the repair of parchment documents. Tylose MH300 was also recently selected as a suspension agent for the leafcasting of a severely damaged medieval manuscript using a purified hide powder (see Wouters, et al. 1992).
Storage: Cellulose ethers are remarkably resistant to mold growth, lasting months unrefrigerated, though ultimately they will attract mold growth. Refrigeration is best for the storage of cellulose ether solutions. The powder should be kept dry, in a tightly sealed container, and away from light.
Caveats: In a recent study by Robert Feller several cellulose ethers including hydroxypropyl cellulose did not perform well under artificial aging. (See Feller 1992.) Although methyl hydroxyethyl cellulose (Tylose) was not included in this particular study, tests in 1984 showed that it yellowed only slightly under artificial aging conditions. (See Adhesives: Methyl Hydroxyethyl Cellulose (MHC).)
  • Cellulose Acetate
General Information: Cellulose acetate is made by the acetylation of cellulose from either cotton linters or purified wood pulps. Acetic acid and a catalyst such as sulfuric acid are used for the acetylation process, which produces a triacetate. The triacetate is hydrolyzed to remove some of the acetyl groups. Hydrolysis is stopped by the further addition of water to the mixture. The acetate is purified by washing and the cellulose acetate flakes are then centrifuged and dried. Two very similar cellulose acetate products, called Cellon and Cellit respectively, were manufactured in Germany at the turn of the century. In the case of ‘Cellit’ the adhesive was sold in liquid form, dissolved in ether. Kodak #4655 and Celanese P911 are two brands of cellulose acetate flakes that are currently used in conservation.
Preparation: Cellulose acetate is soluble in acetone, ethyl acetate and methyl ethyl ketone (MEK). For consolidation purposes it is usually made up in 2 or 3% solutions.
Use: Up until the late 1930's both Cellon and Cellit were used in many European libraries and archives for strengthening paper and parchment documents and for varnishing wax seals. The liquid cellulose acetate was applied with a brush to one side of a document, where it formed a protective varnish coating upon hardening. Cellon or Cellit were considered superior to the cellulose nitrate product Zapon (see below), primarily because it seemed to form a thinner film on the surface of the document to which it was applied. (See Smith 1938, pp.66–67.) Currently, the primary use of cellulose acetate is for the consolidation of flaking media on paper (not parchment) supports. However, a solution of cellulose acetate in acetone has been used for the past 20–25 years at the British Library for the consolidation of flaking paint and loose gesso in parchment manuscripts. (See Consolidation of Media.)
Caveats: Due to their poor aging characteristics cellulose acetate products are not recommended for use in conservation. When used for the strengthening of paper and parchment documents earlier in this century the two cellulose acetate products, Cellon and Cellit, were criticized for the streaks and brownish discoloration that they created. (See Smith 1938, p.67.) Cellulose acetate breaks down creating acetic acid as one of the byproducts which, in significant quantity, would be damaging to a parchment support. The solvents that are needed to dissolve cellulose acetate can also present a problem in its application as a consolidant. Acetone, ethyl acetate and MEK all evaporate very quickly and prevent the adhesive from penetrating into the media being consolidated. Sometimes the cellulose acetate will dry on the brush before it ever reaches the area being treated. In other cases a film of adhesive will be deposited on the paint surface. To counteract these problems the method of application may have to be modified and it may be necessary to later flush the treated area with acetone or MEK, in order to eliminate the shiny deposit left on the surface of the ink or paint.
  • Cellulose Nitrate
General Information: Cellulose nitrate is formed by the reaction of cellulose from cotton linters or wood pulp with mixtures of nitric and sulfuric acids. In varying the strength of the acids, temperature, time of reaction and acid/cellulose ratio many different products with a wide range of chemical characteristics are obtained. Cellulose nitrate was first formulated in 1832 and, in 1864, the process of making a plastic from this material was patented in England. A cellulose nitrate product called Zapon was developed in Germany in the 1890's and was initially used as a paper strengthener for military maps. (See Adhesives: Cellulose Nitrate.) Soon after this period, and up until the late 1930s, Zapon was used in many European libraries and archives for the strengthening or consolidation of manuscripts and documents on both paper and parchment supports.
Preparation: The raw product, which takes the form of a yellowish-white matted mass of filaments (similar in appearance to raw cotton), was usually dissolved in a solution of acetone and amyl acetate. Recipes for cellulose nitrate as used in library conservation often included a small amount of camphor (see Smith 1938, p.54) or vegetable oil as a plasticizer. Sometimes a petroleum distillate was added to slow down the evaporation rate of the solution (see Pederson 1986, p.128).
Use: The German-made product called Zapon was first recommended for use in library and archives conservation at an inter-national conference held in St. Gall, Switzerland in 1898. In the case of paper and parchment documents the liquid cellulose nitrate adhesive was usually applied to one side of the artifact with a brush. The document was then hung up to air dry for about two hours until the film hardened on the surface. (See Smith 1938, p.54.)
Caveats: Cellulose nitrate is a highly unstable product that will decompose rapidly when exposed to moderate air, heat and moisture. Exposure to strong sunlight will cause cellulose nitrate to become acidic, forming a variety of acids and other materials which can damage both the media and the support. Paper and parchment artifacts that have been treated with cellulose nitrate appear cockled and brittle and, in many cases, the ink has bled as a result of the treatment. (See Smith 1938.) For obvious reasons, cellulose nitrate is no longer recommended for use in conservation.

Natural Resins and Waxes

Beeswax has been used in the past for the consolidation of flaking media in parchment manuscripts. (Marconi 1962.) The use of wax for media consolidation has been rejected by more recent authors due to the alteration that it causes in the appearance of certain pigments (Giuffrida 1983). Wax can also attract dust and dirt to surfaces where it is applied. (See Consolidation of Media.)

Synthetic Polymers

  • Poly Vinyl Acetate Solutions
General Information: Poly vinyl acetate is a thermoplastic, odorless, non-toxic, essentially clear and colorless resin that has been used in conservation since 1930. The PVA resins made by the American-based Union Carbide Corporation are known as the AYA series: AYAA, AYAB, AYAC, AYAF, AYAT. The physical properties of these different resins (including solubility, viscosity, softening point, heat-seal temperature, tensile strength and glass transition temperature) vary primarily because of differences in molecular weight. (See Adhesives: Poly Vinyl Acetate Solutions (PVA).)
Preparation: Solutions of PVA resin, which is usually sold in bead form, are prepared by suspending the beads in a cheesecloth bag inside a jar of solvent. Depending on the solvent, it may take 12 or more hours to dissolve the beads with occasional stirring. At room temperature PVA resins are soluble in acetone, alcohols, toluene, chlorinated hydrocarbons and several other solvents. (See Adhesives: Poly Vinyl Acetate Solutions (PVA).) A small amount of water often aids in the solubility of the resin in many solvents.
Use: Among the various PVA resins that are available, PVA AYAC has been principally used in paper conservation as a consolidant. To date, however, it has not been employed for this purpose in parchment conservation. Several PVA resins have been recently used as an adhesive in the repair of objects made from parchment and other untanned or semi-tanned skin materials. A mixture of 25g PVA AYAF and 25g PVA AYAT in 180 ml acetone and 20 ml cellosolve acetate was used for the repair of two 18th c. parchment Battledores at the Winterthur Museum. Although the adhesive worked well the tackiness and working time were diminished because of the volatility of the acetone (Ozone 1985). In two other cases, PVA AYAA was used on its own or in mixtures with ethyl hydroxyethyl cellulose, for the repair of ethnographic objects. (See Vuori 1985, p.6 and Kaminitz and Levison 1988, p.4.)
Caveats: PVA resins are considered to possess reasonable flexibility without the addition of plasticizers. However, since they are permeable to water vapor, they are not recommended in situations where protection from moisture is a priority.
  • Polyvinyl Acetate Dispersions
General Information:
  • Poly vinyl acetate dispersions, which are often incorrectly referred to as emulsions, are made by suspending minute particles of PVA resin in water. PVA dispersions can either be homopolymers or copolymers. Homopolymers require the addition of an external plasticizer, which make them susceptible to embrittlement, discoloration, insolubility and staining. Copolymers do not have these same problems since the comonomer acts as an internal plasticizer, and thus has a stabilizing effect on the adhesive. Many commercial grades of PVA dispersions are available, made by 40–50 different manufacturers. Products currently used in conservation include Jade 403 (Jade Adhesives), Elvace (Reinhold Chemicals), Conservation Materials CM-Bond series, Adhesin A22 (Henkel, Dusseldorf, Germany) and numerous other brands.
  • PVA is a film building adhesive and tends to sit on the surface to which it is applied. It is thus more likely to be reversed with water or polar solvents than other adhesives that penetrate more into the support.(JFM)
Preparation: PVA dispersions are sold as a white viscous liquid. They can be used as is or diluted with water to the desired viscosity. For certain applications one can mix PVA dispersions with other adhesives such as starch paste or methyl cellulose, in order to change the working properties of the material. Although PVA dispersions may sometimes be diluted with organic solvents for the consolidation of unstable media on paper supports this has not yet been done on parchment. (See Consolidation, Fixing, and Facing: Synthetic Adhesive Dispersions.)
Use:
  • Described by Giuffrida (1983) for adhering parchment patches over losses in manuscripts. It is currently used in Italy and Germany for parchment repair.
  • The PVAc, (Adhesin A22, made by Henlke, Dusseldorf) has been tested for use in conservation by Dr. Halmut Bansa in a comparison with other German products. This research has been corroborated by Dr. Robert Fuchs, head of the conservation school in Koln. Currently, this specific adhesive is used in the lab of Dag-Ernst Petersen (Herzog August Bibliothek Wolfenbuttel). The same adhesive has also been used for book restoration at the Bavarian States Library, Munich since the end of World War H. In correspondence, Mr. Petersen writes that “under certain circum-stances, when it is necessary to build a long lasting, flexible and reversible connection Adhesin A22 is used. In order to avoid the splitting off of acid a mixture of two-thirds A22 and one-third CMC is made.”
  • A dilute solution of JADE 403 was recently used to prepare and attach laminates of Japanese paper and goldbeater's skin to the damaged parchment leaves of an Armenian manuscript. (Mowery 1991, pp. 135–136.) Book conservators sometimes use PVA dispersions for certain specific applications, such as in the repair of vellum bindings, where the adhesive's strength and flexibility are desirable features. Combinations of PVA and Klucel-G in ethanol can be used to make Japanese paper repairs more transparent. (See Mending and Filling.)
Caveats:
  • PVA dispersions will gradually release acetic acid over time and therefore their recommended shelf life is limited to 9–12 months. Dispersions are susceptible to damage by temperatures less than 4.44°C (40°F). They can also support mold growth. Additives may dramatically affect the aging characteristics of many PVA dispersions and these may be subject to change by the manufacturers at any time. The reversibility of PVA dispersions is often problematic, largely due to their increased insolubility with age. (See Adhesives: Poly Vinyl Acetate Dispersions (PVA) for further information on aging characteristics, etc.) Tests carried out on Mowolith DM5, a PVA dispersion made by Hoechst in Germany, proved it to be unsuitable for use in the repair of parchment. (See Wouters, et. al. 1992.) The undesirable attraction of dust and the blocking of adjacent leaves has been observed on parchment manuscripts that were repaired in the past with an externally plasticized PVA emulsion. (See Cains 1982/83, p.18.)
  • PVA dispersions vary greatly, and some have better ageing properties than others. In a recent study of poly(vinyl)acetate and acrylic adhesives undertaken at the Canadian Conservation Institute, which used natural instead of artificial aging, JADE 403 performed very well. However, reversibility studies were not performed as part of this project. (See Down, et. al. 1992.)
  • Acrylic Resin Solutions
General Information: Acrylic resins were developed for industrial use in 1931. The n-butyl and isobutyl methacrylates are the acrylic polymers in longest use in conservation, with some of the earliest testing having been done at the Fogg Art Museum in the 1930's. Acrylic resins are addition polymers of acrylic and methacrylic acid and their esters. Rohm and Haas, Philadelphia, manufactures a variety of acrylic resins under the trade name Acryloid (called Paraloid in Europe). Although many other acrylic resins are manufactured by different companies, the Acryloid series has found the widest use in the conservation of parchment and other untanned or semi-tanned materials. Acrylic resin solutions are strong, durable adhesives with excellent flexibility characteristics.
Preparation: Acryloid B-72, a 70% ethyl methacrylate, 30% methyl acrylate copolymer, is available as colorless beads of resin or as a 50% solids solution in toluene. B-72 is unique among acrylic resins in having a high tolerance for ethanol and it is frequently dissolved in this solvent when used in parchment conservation. It is also soluble in several other organic solvents, including toluene, xylene, acetone, MEK, ethyl acetate and amyl acetate. B-72 is insoluble in isopropanol. Acryloid B-48, a methyl methacrylate copolymer, has also been used on occasion for the conservation of non-tanned skin materials. Solutions of acrylic resins are prepared by suspending the beads in a cheesecloth bag inside a container of solvent for 24 hours or more. Sometimes a magnetic stirrer can be useful for speeding up the dissolution of the resin in the solvent.
Use: Acryloid B-72 is currently used in Italy for the consolidation of flaking and friable media on parchment. B-72 is used in Madrid to stabilize media on parchment manuscripts and documents prior to immersion in a bath of polyethylene glycol. (See Vinas 1987.) A tissue coated with an 18% solution of B-72 in toluene was used in 1985 at the Turin Archives, Italy, for the lamination of a perforated parchment document. In this case the adhesive was activated with heat. A mixture of Acryloid B-72 and EHEC (an ethyl hydroxyethyl cellulose manufactured by Hercules) has recently been used for the repair of ethnographic skin objects (see Vuori 1985, and Dignard 1992) and might also be applicable to parchment repair. (JS) A solution of Acryloid B-48N in toluene has been applied to small pieces of goldbeater's skin, which were then used to repair tears in bird skin. In this case the adhesive was activated with toluene (see Kaminitz and Levinson 1988).
Caveats: According to Feller (1971), Acryloid B-72 is the most reversible of the acrylic adhesives; it remains soluble and does not cross-link significantly upon aging. Other acrylic resins, such as Acryloid B-48, tend to cross-link through heat and ultra-violet and visible light exposure. They generally remain colorless and transparent over time. In recent tests, solutions of Acryloid B-72 in ethanol and in diacetone alcohol were rejected as adhesives for parchment repair because of their poor water vapor permeability and because of the surface damage that was caused in attempting to reverse parchment to parchment joins that had been executed using B-72. (see Wouters, et. al. 1992).
  • Acrylic Resin Dispersions
General Information: Acrylic resin dispersions were formulated in 1953 for use as painting media by artists and for industry. Acrylic dispersions are prepared by emulsion polymerization. Those currently used in conservation are copolymers of acrylic resins: blends of ethyl acrylate and methyl methacrylate made from monomers of methyl, butyl, and other longer chain esters of acrylic or methacrylic acids. Although many different acrylic resin dispersions are currently available, the Rhoplex series made by Rohm and Haas, Philadelphia, are the only ones that have been used to date for the treatment of parchment. The Plextol series, made by Rohm Gmbh in Germany, are widely used in Europe but are not considered to be a direct substitute for the Rhoplex resins. (See Adhesives: Acrylic Resin Dispersions.)
Preparation: Acrylic resin dispersions are sold as a milky white liquid of resin solids dispersed in water. They can be used as is or diluted with water or organic solvents. In the manufacture of Library of Congress heat-set tissue Rhoplex AC-234 and AC-73 are mixed together and painted out on glass. Lens tissue is dropped in place on the wet adhesive and allowed to air dry. (The method used at Trinity College Library, Dublin is the same except the adhesive formula is one part Plextol M630 and two parts Plextol B500, diluted in six parts of water. (See Cains 1992 p.154.) Once peeled off the glass the coated tissue is ready for use, either as a heat-activated or solvent-activated repair material.
Use: Rhoplex AC-234 has been successfully used, in dilutions with water and/ or organic solvent, for media consolidation on both paper and ivory supports. (See Consolidation, Fixing, and Facing: Rhoplex AC-234.) However, this particular adhesive has not been used for this purpose in the conservation of parchment artifacts. Heat-set tissue, made according to either the library of Congress formula or the Trinity College Library formula (see above), has been used both directly and indirectly in the repair of parchment artifacts. More recently, transparent membrane has been coated with the two acrylic resin dispersions, Plextol M630 and Plextol B500, for use in parchment repair. (See Adhesive-Coated Tissues and Membrane.)
Caveats: The aging properties of acrylic resin dispersions can vary widely according to how they are manufactured (especially in terms of the additives they might contain) and also how they have been applied to an artifact. In theory, all acrylics are stable to light, resistant to heat and oxidation, and have little tendency to yellow over time. (See Adhesives: Acrylic Resin Dispersions: Aging Characteristics.) Recent research at the Canadian Conservation Institute, which used natural instead of artificial aging for testing a wide variety of polyvinyl acetate and acrylic adhesives, found that the acrylic resin dispersions performed very well. However, among the acylic resins that were tested Rhoplex AC-73 was found to become very brittle and, along with Rhoplex AC-234, its pH fell within the acidic range (i.e. below pH 5) after aging (Down, et al. 1992).
  • Polyamides
General Information: Soluble nylon is a chemically modified form of nylon produced by treatment with formaldehyde. From about 1950–1970 soluble nylon was widely used in conservation, for the treatment of stone, ethnographic objects, paper and parchment. The brand used in conservation, Calaton CA or CB, was sold by Imperial Chemical Industries. The English product had the trade name Maranyl. Although soluble nylon is still occasionally described in some publications it is no longer recommended for use in conservation, due to its poor aging properties (see below).
Preparation: Soluble nylon is available as a white powder and is generally dissolved in alcohol or alcohol cosolvent systems that include water, aromatic hydrocarbons or chlorinated hydrocarbons. Heat is usually needed for the complete dissolution of the material and the recommended working temperature is 40°C with normal working concentrations of 2–5%. (See Plenderlith and Werner 1971 p.375.) Although soluble nylon could be used in spray form it was generally applied with a brush.
Use: Beginning in the 1960's soluble nylon was recommended for use in conservation by A.D. Baynes-Cope and Anthony Werner of the British Museum Research Laboratories and, upon their advice, it was included in the British Standard for Archival Repair.(NP) Soluble nylon was recommended for the reinforcement of very limp, degraded parchments (see Werner 1974, p. 17 and Johnson 1980, p.25) and for the consolidation of flaking or friable paint on parchment supports. Sometimes the soluble nylon was dissolved in warm methanol for media consolidation. Roger Powell used a 3% solution of soluble nylon in industrial methylated spirit for consolidation of media and degraded areas of skin during the treatment of an early illuminated manuscript on parchment. (See Powell 1965, p.264 and Powell, 1974, p.181). A warmed solution of 5% soluble nylon in ethanol was used at the Walters Art Gallery for paint consolidation in illuminated manuscripts, ca. 1960–77 (Drayman 1968–69). Up until the 1960s soluble nylon was frequently used at the Public Record Office, London for the reinforcement/consolidation of parchment documents.
Caveats: When heated in water parchment can begin to shrink at temperatures as low as 40°C (Reed 1975, p.94), which is the recommended working temperature of soluble nylon. Soluble nylon oxidizes upon exposure to light and high temperature and over time it cross-links and become insoluble. In addition, films of soluble nylon become brittle and eventually rupture or pulverize, thus causing damage to the media or support to which it is applied. For these reasons, soluble nylon is no longer recommended for use in conservation.
  • Proprietary Formulations
The following formulations have been used primarily in Russia for the consolidation of friable media and degraded parchment. Although testing may have been carried out by the scientists who originally introduced these materials for used in parchment conservation information on their ageing properties and long term stability is not readily available in the U.S.
  • VA 2 EHA: A co-polymer of vinylacetate with 2-ethylhexyl acrylate (VA 2 EHA) has been used in Russia for paint consolidation in illuminated manuscripts. (See Bykova, et al. 1976 and Mokretsova, et al. 1978.)
  • CEV: A partially hydrolysed co-polymer of vinylacetate with ethylene (CEV) has been recently used in a 2:1 alchol/water solution for the consolidation of flaking paint in Greek illuminated manuscripts (Bykova 1993). According to the author this material, whose properties were investigated by two Russian scientists as early as 1979, is very stable and easily reversed in alcohol.
  • Ftorlon F-24L: A soluble fluoroplast currently used in Russia for the consolidation of flaking/friable media and for the consolidation of degraded parchment. Fluoroplasts are products of the polymerization and copolymerization of fluorolefins and they are considered to be quite inert with respect to their action in air, moisture and oxygen. (See Bykova et al. 1976, Mokretsova, et al. 1978 and Bykova 1993.)


Lubrication of Horny, Desiccated Parchment[edit | edit source]

At one time the lubrication of parchment was a widely accepted practice and the rationale for this treatment was often presented as follows: “The most widely spread damages of parchments are different kinds of deformations. This is precisely why the main attention in restoration practice is paid to softening and straightening, that is, the elimination of deformations”. (Yusupova 1980, p.57.) The proteinaceous natural glue component of the processed parchment sheet, which cements in place the fibrous structure, was thought to become brittle over time and the natural plasticizing or grease component of the “glue” to become ineffective so that parchment lost its strength and flexibility. (Wächter 1962, p.23.) Lubrication met two needs of such deteriorated parchment: the softening of brittle sheets and the regeneration of the parchment size.

Lubrication has also been used as a preventive procedure. By coating the fibers of the dermal network with oils and fats which are “hydrophobic, soft and easily sheared” its water resistance is enhanced and its variability with changes in ambient environmental conditions, a result of its inherent hygroscopicity, is reduced. (See Reed 1972, pp.170–171; Vinas 1975, p.111.) Lubrication may have been inspired by practices recorded in medieval recipes for preparing parchment. Many fats listed there are fairly polar lipids which can bind small but definite amounts of water to provide the basis of parchment handle and flexibility while minimizing absorption of excess water vapor and the subsequent risk of biological decay. (Reed 1972, pp.170–1.)

The uncertainty surrounding lubrication may account for the many recipes found in the conservation literature, “each claiming to be excellent and universally applicable”. There is confusion also because it has been assumed that “what is permissible with leather is also feasible with parchment ... In fact parchment requires very little in the way of fatty substances to improve its handle...”. (Reed 1972, p.236.)

More recently the practice of lubrication has been largely abandoned in favour of water-based softening systems. Since parchment relies for much of its flexibility and general handle on its moisture content, it is the loss of water, not oils and waxes, that is largely responsible for parchment's loss of flexibility and its embrittlement (Clarkson). Instead of lubrication, the literature now concentrates on methods of returning optimal moisture content to the skin and its sufficiently even distribution in the parchment. It is recommended, therefore, that the conservator first try the hydration and flattening methods described in 18.4.7., 18.4.9 Local Treatment, and 18.4.10. If these methods are not successful, as may be the case with severely distorted and shrunken material, some of the methods described in this section may be resorted to as long as their inherent risks are clearly understood. Carefully test all constituents prior to application of any lubricant.

Another reason why these methods have been abandoned is a change in preservation philosophy: “Techniques and materials that change the original character of the [object], such as impregnation with synthetic polymers, humectants, plasticizers or lubricants are ... not necessary if the storage or exhibition environment is stable and controlled (55–60%) the equilibrium moisture content of the material maintained at the correct level to keep it flat and pliable.” (Cains, 1992)

Polyethylene Glycol (PEG)

Used in Madrid for the lubrication of horny parchment and also for general relaxation of cockled parchment; the most useful and preferred is PEG 400. (See Vinas Torner 1979.) Carbowax has been used in molten form to separate leaves of a heat-damaged parchment manuscript. It has also been used in combination with lubricants, e.g. gelatin and glycerol, to relax brittle, desiccated parchment. (Werner 1974, pp.17–18.) Moderate success was achieved by brushing PEG 200 on a distorted, heat-damaged parchment tensioned on a strainer to investigate the potential of simultaneous softening and tensioning. (Tanasi 1984, p.23.) Useful where inks are unstable in water and alcohol solutions.

An experimental technique using PEG was recently developed by Dag Ernst Peterson for the treatment of a severely water-damaged parchment book. The technique itself was developed by Vinas (Spain) and recommended to Peterson by Prof. Alicja B. Strzelczyk, Kopernikus University, Torun, Poland. Mr. Peterson's experimental work was to modify the Polish procedure for treatment of the Theuerdank, a 16th printed book on parchment that had been severely damaged by water. His new technique is based on the idea of introducing PEG into the skin in a very controlled manner, rather than using the more liberal quantities that are recommended by Vinas. The vellum leaves were transparent and stiff from the water damage and the original napped surface was flattened. With a defined sequence of applications separate solutions of calcium hydroxide in water and polyethylene glycol were applied indirectly to the parchment. The leaves were then dried under tension using C-clamps. The timing was critical for each treatment and varied depending on the condition of the individual leaf. The treatment was successful in making the vellum opaque and flexible and in recreating the original velvet nap of the skin.(DEP)

Urea, With or Without Spermaceti Wax

10% urea in ethanol and water was applied to surface of a parchment document through tissue paper so the inks would not be disturbed or softened. Reduced folds and creases effectively (O'Hoski 1976, p. 67, see also her note 6). Moisten parchment thoroughly with above or dip it in its 5–10% solution, then simultaneously dry and press. After partial drying Yusupova 1980, p.58, recommends additional greasing treatment with 1–2% alcoholic benzol suspension of spermaceti wax (alcohol-benzene spermaceti emulsion).

Parchment Size With Wine Vinegar and Alcohol

(see Lubricants: Parchment Size with Wine Vinegar and Alcohol.)

Leather Dressing

Pliantine proved to be more suitable for relaxing the parchment components of Javanese shadow puppets than either British Museum Leather Dressing and neatsfoot oil. After application, excess Pliantine was not removed for several months to ensure good penetration. Then the surplus was removed with solvent (hexane, petroleum ether). Impregnation caused temporary slight darkening of applied colours (Gowers 1975, pp.4–5).

Glycerin

(see Lubricants: Glycerin.)

Alcohol

  • Methanol:
Giuffrida describes the successful use of methanol, in a bath or as a vapor in an enclosed container, to relax badly distorted, possibly gelatinized, parchment (1983, p.32). To remoisten dried out skins and make them more flexible prior to retensioning, parchment sheets can be gently rubbed all over with cotton wool dampened with alcohol (containing some water, not absolute alcohol). Take great care not to dislodge ink particles. Do not use on illuminated leaves. Slow treatment should never be carried out using a solvent containing water because of the greater danger of bringing about (further) gelatinization (Giuffrida, 1983, p.31–32).
Cains, p.51, describes immersion technique of vellum leaf in methanol followed by insertion in polyethylene envelope (to inhibit evaporation of the methanol and contact with this toxic solvent) followed by manipulation to ease out distortion. He uses ethanol or isopropanol and water for local dampening of horny, relatively impermeable areas of skin.
  • Ethanol:
Immersion of distorted, fire-damaged parchment rolls in a water/alcohol solution of 60% ethanol for 24–48 hours permitted unrolling. This was followed by tensioning and repeated brushing with the water/alcohol solution over 3–4 days so the parchment never dried out. When this treatment was followed by swabbing with or immersion in PEG200 the result was more “perfectly flat and obviously more soft than similar parchments not treated with PEG” (Tanasi 1984, pp.23–26).
Dreibholtz (1991) describes use of alcohol and water mixture (4:1) on shrunken creased Middle Eastern parchments: spray hair side first to postpone curling of edges, place between wax or silicon paper and weight edges with small weights. Repeat this process as necessary. After final spray, put parchment into press under very light weight. After one day, replace the silicon with blotting paper. The object is pressed for 4 weeks or longer.

Other Lubricants

  • Lanolin Emulsion: 1% anhydrous lanolin in ethanol and water to lubricate fibers (for preparation and use see O'Hoski 1976, pp.69, 76).
  • Milk: Because the original “softness” of parchment was due to its content of natural grease, the addition of small amounts of acid-free fatty substances, such as milk, were thought to be helpful. Rubbed into the parchment, milk has been reported “to clean it and make it a little greasy”. An associated risk was the potential generation of lactic acid (Wächter 1962, p.24).


Lubricants[edit | edit source]

Lubricants are plasticizers which have been introduced by conservators into parchment to enhance the immediate and long-term flexibility of parchment artifacts and to permit reduction of distortions. According to Sully (1992, p.50) the lubricant should ideally “cause a minimal change in surface appearance and should conform to the principles of reversibility and minimum intervention.” However, since the majority of lubricants listed below have been found to alter the structure and appearance of parchment, on both an immediate and long-term basis, they are not currently recommended for use in conservation.

Parchment Size with Wine Vinegar or Acetic Acid and Alcohol

  • General Information: Parchment size is an extract of the cohesive materials from new parchment. It is a viscous colloidal solution which is often preferred for lubrication because it is chemically compatible with parchment (see Collagen-based Adhesives). Adding acetic acid helps to solubilize the collagen and produces a more fluid size, allowing it to be spray-applied or applied at room temperature. Alcohol, added as a thinner, improves the penetration of the parchment size; it also has a bactericidal effect. Ethanol is widely used but Reed (1972, p.223) recommends isopropanol which “goes in more slowly, penetrates more deeply, takes longer to evaporate and allows more of the size to be absorbed by the parchment before it sets”.
  • Preparation:
Wächter's recipe: prepare parchment size (Collagen-based Adhesives). Combine 1/3 parchment size, 1/3 wine vinegar (5% acetic acid) and 1/3 ethyl alcohol. Modification of Wächter's recipe to reduce acetic acid content: 10% glacial acetic acid in distilled water. Add 1 drop to each 5 ml parchment size.
Acetic acid must be added before the alcohol, otherwise hydration relationships within the colloidal system are affected with the production of turbidity and granular precipitates (Reed 1972, p.224).
  • Use: Brush application or spraying. Better penetration of the size results if parchment is humid at time of application. (Giuffrida 1983, p.38.)
  • Caveats: The use of acetic acid is controversial; it will soften parchment and should be used in very low concentrations. It can intensify colors (Wächter 1962, p.24) and affect pH-sensitive colors.


Polyethylene Glycol

  • General Information:
Polyethylene glycols are humectants - hygroscopic materials which exhibit moisture regulating properties in parchment. They supply lubricating moisture to a desiccated skin, thus facilitating fiber movement. Carbowax (Union Carbide) is a polyethylene glycol wax which ranges from soft to hard and from liquid to solid with increasing molecular weight (e.g. PEG 200 to 600 are liquids of increasing viscosity). As the molecular weight and viscosity increase, PEG becomes decreasingly hygroscopic.
According to the literature polyethylene glycols have the following properties: lubricating, non-volatile, water-soluble, neutral pH, non-corrosive, non-flammable, relatively non-toxic.
  • Preparation: PEGs require little preparation and can be used directly from the container.
  • Use: Hygroscopic stabilization treatment is achieved by maximum penetration of the PEG into the parchment. The best procedure is to use PEGs of low molecular weight (200–400) applied by immersion which should continue until the parchment becomes transparent; this indicates its saturation. Can also substitute continuous applications with brush or sponge, keeping the parchment between 2 sheets of polyethylene so that it can be observed. The parchment is tensioned and flattened. Final drying/flattening between blotters and under pressure. (Vinas 1987.)
  • Caveats: Slow acting (days, weeks reported in the literature). Thick parchments may need prior humidification to facilitate penetration of the PEG and reduce treatment time. Transparentizes parchment when applied; opacity is regained after several hours of air drying. Can affect media by changing their refractive indices and making them appear more saturated.


Urea

  • General Information: Urea is a polar substance which interacts with the polar groups of collagen and weakens the interaction between the polypeptide chains. It separates the latter reducing hardness and deformation (Belaya 1969/70, p.27). Spermaceti wax, sometimes added to urea when used for softening parchment, is an animal wax obtained from the head bones of the cachalot (sperm) whale (extraction process described by Reed 1972, p.238). It has a low softening temperature (40–44°C) and is easily emulsified with water.
10% alcohol solution of urea:
  • prepare a 50% solution of alcohol: dilute 106 ml of 96% alcohol with distilled water to 200ml.
  • prepare 10% alcohol solution of urea: dissolve 10g urea in 100ml of 50% alcohol.
  • prepare a 20% spermaceti solution: dissolve 20g spermaceti in 100ml pure benzene (!) in a phial with a ground glass stopper.
  • prepare a 2% spermaceti wax emulsion: pour 10ml of this 20% spermaceti “into benzene” (quantity unclear?) in a phial with a ground glass stopper: add 90ml of 96% alcohol while stirring constantly. Cork; shake vigorously until emulsifies. Stir before use.
  • Use:
Use of urea in aqueous or water-alcohol solution, with and without spermaceti wax, was first described by I.K. Belaya (1969). It was formerly used extensively in Russia and by some Western restorers. Possibly still used at the British Library for the general softening of parchment (Quandt 1993).
Very deformed and brittle parchment is cleansed with water followed by rapid drying with 96% ethanol; then it is immersed in the urea solution. Next it is pressed. 2% spermaceti wax emulsion is rubbed in to increase the strength and elasticity of the parchment. (Detailed instructions given by Belaya 1969, pp.49–51.)
  • Caveats:
Urea solutions may partially hydrolyse the collagen and also affect the parchment similarly to water-based systems (Yusupova 1980, p.59). Its use in Russia has now been discontinued because manuscripts previously treated with urea have become more transparent (Yusupova 1980, p.59) or to have darkened (Quandt 1993). Urea is now used in Russia exclusively for the separation of sheets stuck into blocks. (Yusupova 1980, p.61.)
The use of spermaceti wax is often accompanied by formation of an uneven white coating (excess spermaceti) which can be easily removed with benzene. (Yusupova 1980, p.60.) It may become rancid through oxidation. Toxicity of benzene contraindicates its use.


Leather Dressings

  • General Information: Proprietary leather dressings (containing lanolin, neatsfoot oil, etc.) have sometimes been used to soften and lubricate parchment. Neatsfoot oil is a yellowish, nearly odorless oil extracted from the feet of cattle and sometimes sheep. The solid components crystallize out at low temperatures and are filtered off in the production of cold tested neatsfoot oil (Landsmann 1993, p.30). Lanolin or unbleached wool wax (softening range - 58–62°C), is an animal wax that occurs in many forms. It has excellent emulsifying action and does not easily go rancid. Good penetrating power makes its application easy. Beeswax, also an animal wax, (softening range 62–66°C), is slightly harder than lanolin and is used to give body to the dressing. (Reed 1972, pp. 238–239.) Cedarwood oil, a pale yellow oil, is obtained by treating cedarwood with hot water and steam. It is sometimes used as a thinner, as well as a vehicle to control the consistency and composition of leather dressings; however, cedarwood oil is used mainly for its fungicidal action. (Reed 1972, pp.240–241.)
  • Preparation: British Museum Leather Dressing (200g anhydrous lanolin, 15g beeswax, 30 ml cedarwood oil mixed into 350 ml hexane - e.g: proportions differ from recipe to recipe - to form a paste). For preparation details see Reed 1972, p.242. ‘Pliantine’ is a later variation of BMLD in which the hexane was replaced by trichlorethane (Genkleen). Talas leather dressing: the beeswax has been replaced by neatsfoot oil. (Landsmann 1991, p.33.)
  • Use: According to Reed (1972, p.242) the parchment is first conditioned to a relative humidity of 60–70%. Rub paste evenly over surface with finger. Leave for a day or two at room temperature; then decide whether further treatment is necessary. With parchment one application is usually enough.
  • Caveats: Neatsfoot oil and British Museum Leather Dressing left the surface of the parchment tacky. (Gowers 1975, p.4–5.) Considerable damage may be incurred by this treatment. (see Reed 1972, pp.242–243.) Lubricants should not be applied to non-tanned skins as they will unacceptably alter appearance - increased transparency. Glossy finish imparted by beeswax component may be unacceptable on parchment. (Reed 1972, p.242.)


Glycerin (also known as Glycerol)

  • General Information: Formerly recommended for the lubrication of horny parchment.
“Glycerol is neutral in reaction and acts as an antiseptic, even when largely diluted; ... It is soluble in a mixture of 2 volumes of absolute alcohol and 1 volume of ether [ether not identified; could be ethyl or petroleum ether] a fact which may be employed to separate it from the sugars, gums, gelatin, and various salts. Glycerol also dissolves ... the vegetable acids and all deliquescent salts. It is highly hygroscopic, absorbing as much as half its weight in water when exposed to damp air.” (Allen p. 451.)
  • Preparation: Used as an aqueous solution with a small addition of spermaceti wax (Mizin's spermaceti emulsion) in an organic solvent: 96% alcohol: 95ml; glycerin: 2ml; 4% spermaceti wax in benzene: 3ml (Belaya 1969, p.23). Glycerin is also a constituent of egg softener and lanolin emulsions, see 1.3.2.G Lubricants.
  • Use: Glycerin emulsions usually applied directly to the surface of a parchment artifact.
  • Caveats: Glycerin softens parchment greatly but also reduces its strength. It increases the hygroscopicity of parchment by 150–200%, making it sticky and leaving it vulnerable to mold and other micro-organisms. Concentration of spermaceti in Mizin's recipe is so low that practically no softening is obtained. (Belaya 1969, pp. 25, 27.) Glycerol renders the parchment transparent; also the softening effect is not permanent. (Wächter 1962, p. 24)


Alcohol

  • General Information: Non-hygroscopic polar solvents (isopropanol, ethanol, methanol) function as softening agents by hydrogen bonding with hydroxyl groups in the fiber structure without causing hydration. They have been used to reshape water sensitive materials such as degraded, distorted vellum (Sully p.50).
  • Preparation: Alcohol solutions require no special preparation when applied to parchment, other than mixing to the desired proportions.
  • Use: Current practice is to immerse parchments in 70% ethanol-30% water bath though water may vary between 20%-50% and ethanol between 50%-70%. (Lefevre & Chahine 1986, p.165.) Pure methanol has also been found extremely useful in the softening of parchment yet this practice has been largely discontinued because of the extreme toxicity of the solvent. The conservation literature also notes the use of softeners such as lanolin, egg-yolk, spermaceti, glycerin, etc., to alcohol baths. (Lefevre and Chahine 1986, p.166.)
  • Caveats: Methanol is highly volatile and toxic. It is unpleasant to use and has no advantage over ethanol/water solutions (Cains 1982/83). Immersion in these solvents must be followed by tensioning/pressing or the parchment will dry distorted. Too strong a pressure may result in transparency of the parchment. The presence of water in alcohol/water solutions may cause alteration of surface preparations and coatings and may have a damaging affect on the media. Alcohols may also cause some dehydration of the skin.


Other Lubricants

  • General Information: Emulsion treatment has been undertaken to compensate for the fatty substances postulated to have been lost by the parchment through natural ageing and poor environmental conditions. The qualitative and quantitative compositions of emulsions vary greatly.
  • Preparation and Use:
According to medieval recipes, to exploit effects of oils and fats fully, their even application was essential. Emulsoid systems (e.g. egg yolk, milk, butter suspensions, etc.) worked thoroughly into the wet pelt, before drying on the stretching frame, softened the handle of the parchment and enhanced its water resistance. (Reed 1972, p.170.) Technique of use of natural emulsifiers is described by Yusupova 1980 p.58.
Egg yolk softener/ egg emulsions: egg yolks contain phospholipids, highly polar fats which bind readily with water. Combine into a thick paste egg yolk: 30–40g, glycerine: 20–30ml, distilled water: 20–30ml, ammonia: 3ml, spirit of soap: 10ml, thymol: 2% of the whole mixture. Use as directed above for lanolin emulsion (Belaya 1969, p.24; for Reed's recipe 1972, p.245).
Spermaceti wax (described above in Urea). Spermaceti-glycerin emulsion: for its preparation (see Glycerin above) Spermaceti-lanolin emulsion.
Lanolin or wool wax (described 18.3.2.D Leather Dressing). Lanolin emulsion: 96% alcohol: 50g, distilled water: 100g, lanolin: 5g, glycerine 10g, neutral soap: 2g. Parchment is humidified, egg-softener (see below) or lanolin emulsion is applied, the parchment is “straightened out on glass” and partially dried; then it is pressed between sheets of filter paper and cloth (Belaya 1969, p.24). See also Reed 1972, p.238 for its preparation.
  • Caveats:
The use of the above lubricant mixtures is now outdated for a variety of reasons. They have not proven to achieve the necessary softening effect on desiccated parchment. It has proved difficult to determine dosage and so application has resulted in stickiness and transparency of parchments.
With egg softener and lanolin emulsions the text may be damaged by their application and the parchment may become transparent. The former is also attractive to micro-organisms (Belaya 1969, p.25).


Case Studies[edit | edit source]

Conservation of Early Qur'an Fragments[edit | edit source]

(Ursula Dreibholz, edited by Walter Newman)

During the restoration of the west wall of the Great Mosque in Sanaa, in 1972, over 40,000 manuscript leaves and fragments from the first to the fifth Higri (700–1200 A.D.) were discovered between the outer roof and inner ceiling of the mosque. This was most likely a place to discard Qur'ans which could not be used any more because they were damaged, but which could not be simply thrown away because of their sacred nature. As soon as the importance of (he find was realized, the question of preservation arose. In 1980 an agreement was reached between Germany and Yemen to set up a special project, sponsored by the German Foreign Ministry, to catalog and conserve the artifacts.

Fragments from almost 1000 different volumes of the Qur'an have been distinguished but not one of these volumes is complete. Leaves range in size from 50 × 80mm to 400 × 450mm. They date as early as the seventh century A.D., and include printed texts as late as the 19th century. Most of the manuscript is in brown or black ink and color has been used for the dots of the vocalization marks and other pronunciation signs as well as occasional decorations such as verse stops and sura headings. The number of fragments written on parchment has been estimated at twelve to fifteen thousand. There is also a large but uncertain number of fragments written on paper. The parchment manuscripts have been given priority so far, as they include examples which are more significant to early Qur'anic paleography.

At the time of their discovery the condition of the objects varied from very good to almost totally destroyed. It was immediately obvious that the material had been a source of food for rodents and insects. However, much of this damage may have occurred prior to storage in the roof. Rain from the undetected leaking roof had mixed with centuries of dust to form encrustations upon a great many of the manuscripts, some of which resembled bricks. The water had caused inks to bleed or even disappear completely; there were severe cases of parchment shrinkage and in the worst examples the parchment skin had irreparably deteriorated. Still, despite localized damage from rain water, many of the parchment leaves were relatively well preserved, thanks to the dry climate of the area. Relative humidity averages between 25–35% most of the year, and only goes up to 50–60% during the two rainy seasons. Although the leaves are very dry, stiff, and brittle, they are preserved and can be successfully relaxed in the humidity chamber. Other damage took the form of heavy pleating and creasing, tears, and deliberate mutilation where areas of the leaves had been cut out.

The immediate aim of the initial conservation treatment was to consolidate the material so that it could be examined. This mainly involved gentle relaxation and cleaning of the items. Tears were only repaired when it was deemed that the item could not otherwise be safely handled. Extremely fragile leaves were placed in polyester film sleeves which were open on two sides to assure air flow and easy retrieval. Although the treatment applied to most of the items was simple, each item was individually assessed and treated according to its particular needs.

The previous conservator had reportedly used urea for treating the parchment. She did not use a humidification chamber at all, but applied urea solution liberally to the parchments and then pressed them while still wet. Consequently, some of the leaves have a shiny, translucent, and alien appearance.

Since a purpose-built conditioning chamber was not available, a much simpler but effective device was employed. This was constructed by placing a shallow tray of water at room temperature into a larger container. Nylon netting, with its edges glued between strips of strong plastic to give support to the parchment leaves, was suspended above the tray. The nets were in turn supported by frames cut out of sheets of foam rubber, which allowed sufficient space between the nets to accommodate the deformed parchment leaves. The uppermost net was then covered by a layer of moist blotting paper, while a wooden board with a thinner foam rubber glued inside it closed the chamber tight enough to create an appropriately humid atmospher. The humidity level could be varied by leaving the cover slightly open, or by not using moist blotting paper, or by leaving the pages in the chamber for longer or shorter periods of time.

After an overnight stay in the chamber the leaves were easily unfolded and unrolled, and pages stuck together were separated with care.

Dirt was then cleaned off with a cotton ball moistened with a solution of four parts ethanol and one part water. After several tests this was found to be the most efficient mixture for this purpose. When used carefully it removed dust and dirt effectively but did not affect the inks or pigments. It also softened fly spots and encrustations to the point where they could be removed easily with a scalpel. The alcohol seemed to help distribute the moisture evenly throughout the parchment, while at the same time preventing it from becoming too wet. The hair side was always dampened first because it does not absorb moisture as readily as the flesh side, and this helps prevent the edges from curling. During local dampening it could be observed that parchment which was exposed to excessive moisture or to water at an earlier time (which was clearly indicated by increased decomposition, shrinkage, or discoloration) was more hygroscopic and reactive to moisture even if it had been dry for a long time.

Next came what proved to be the most difficult operation, that of tensioning the fragments in order to ease out creases, stretch shrunken parts, and smooth out curled edges. The irregular shapes of the fragments, and their fragile nature, meant that conventional methods of “pinning out” could not be used. The following technique was employed instead. The humidified and relaxed item was placed between sheets of waxed paper or silicon paper, weights were gradually placed over the object section by section, and the parchment was allowed to dry slowly. Some sections had to be manually stretched or manipulated. Sometimes the procedure had to be repeated several times, although generally once was enough. As the item dried, the parchment was checked about every ten minutes, especially to make sure that no edges were folded over, which would cause permanent damage under pressure, and heavier weights were placed on the item. When almost dry, the parchment was lightly sprayed with the ethanol/water solution, placed between sheets of waxed or silicon paper, and placed in a press with very light pressure. After a day had gone by, when there was no longer a risk of paper fibers sticking to the damp ink or of the ink offsetting, the waxed paper was replaced with blotting paper. This process was monitored over a period of a week or even until the moisture content of the parchment was stable and there were no longer signs of the parchment tending to move, and then the fragments were left in the press between blotters for another three weeks or even longer. Following this treatment they had usually regained sufficient flexibility and stability to have their textual content examined.

The main concern over the last few years has been the permanent storage of the collection. The huge task of cataloging the material relies on quick retrieval, so the system has to be flexible enough to accommodate newly cataloged items which are to be reunited with other leaves from the same codex. As mentioned above, extremely fragile leaves are placed in polyester film sleeves open on two sides. All the leaves are placed in flat folders which are lined with thin acid-free board. A sheet of polyester film is attached to this lining and then folded back over the object. In this way when the upper part of the folder is lifted one can easily see the object, while it is still protected by the sheet of polyester film and cannot fall out or curl. For larger and thicker parts of volumes a sheet of polyester film is attached to the inside of a wrapper of acid-free board. The polyester film covers the top leaf and permits instant visibility when the board wrapper is opened. A window is also cut in the top board for visibility. The two boards confine the leaves like the covers of a book. They are tied together with linen tape, and the unit is stored in a drop-spine box. The boxes are stored horizontally, in the tradition of the Islamic book, in specially fitted cabinets. There is a folder for every signature, and the labels for over-sized or bulky objects which are too big to fit into the regular folders are color-coded so that one sees at a glance if the item is kept in a box or in the cabinet for oversized volumes.

The fragments are too weak to be resewn, and since the volumes are incomplete there is always the possibility that other leaves will come to light from among the unrestored material. So all consideration of rebinding, as well as of mending tears and filling in lost areas, has been postponed until the stabilization of the collection is complete and a more comprehensive program of priorities has been established. The conservation and storage facilities are installed in the Dar al-Makhutat, the manuscript library, which is across from the Great Mosque in the old city of Sanaa, where the fragments were found.

(A version of this report appeared in Paper Conservation News, Vol. 10, No. 69, March 1994, written by Ursula Dreibholz and edited by Edward Simpson. This version was edited by Walter Newman, incorporating additional information provided by Dreibholz.)

Housing of Dead Sea Scroll Fragments for Exhibition[edit | edit source]

(1993–1994) (Doris Hamburg)

The twelve Dead Sea Scroll fragments chosen for exhibition in the United States (1993–1994- three venues) are quite variable in terms of visual appearance and condition, though all are considered fragile. Some are very dark; others are quite light in color. In some cases there has been delamination on the top layer and tenting along cracks. Insect and/or mold is apparent on some. The thickness varies as well. Brittleness is a characteristic shared by most. Some scrolls were previously lined with lens tissue and a resin adhesive. All have breaks, losses, and staining. Many have undulations, and are not flat. In general the carbon ink appears well adhered to the support. The skin materials of the Dead Sea Scrolls are thought to come primarily from sheep and goats, and to have been partially tanned. The Scrolls date from the third century BCE to the first century CE, based on historical, paleographic and linguistic evidence, and confirmed by carbon-14 dating.

In considering options for the exhibit housing, it was clear that a modular system that would require no direct handling of the scrolls during the exhibit period was needed. Another focus was to create a system that would minimize changes in relative humidity and would avoid any flexing and movement of the fragments. The scrolls were being exhibited and stored between venues in institutions with good environmental conditions and monitoring; all scrolls would be hand carried between venues. It was considered preferable to avoid the use of adhesives. To facilitate packing issues, the outer dimensions for ten of the twelve fragments were standardized.

A layered system that formed a “package” was developed, as illustrated. The acrylic sheeting filters ultraviolet radiation and provides a physical barrier as well as rigidity to the package. A spacer below, made from alkaline buffered rag board, separates the scroll fragment from the the acrylic sheet. Two mats were cut to hold stretched pieces of polyester netting (Tetex- aka Stabiltex). The openness of the net weave and the color allowed viewing of the scroll fragment. None of the scroll fragments showed evidence of the skin softening due to gelatinization, as has been reported in some fragments that were subjected to higher humidities. If this type of softening and gelatinization had been evident, and/or if the environment was not to be controlled, this system would not have been chosen. The polyester fiber is smooth and has long term stability. Silk has been used in other contexts for related housings; it has a scaled fiber morphology and has less long term stability. Polyvinyl acetate (pva) emulsion was applied to the inner side of each mat, allowed to dry and the polyester net was applied in position with a tacking iron. The weave orientation of the polyester net on the second mat was askew to the first to minimize the possibility of a moire effect when placed together. Double sided 3M 415 acrylic tape was applied to the inside of one of the mats. The scroll fragment was placed between the two net mat layers, held together by the tape. The fragment was held in position by sewing around the outside of the fragment (not touching) using thread from another piece of the polyester netting. The sewing was visible only in some lighting situations, and was generally note seen by the viewer. The next layer was a natural, unbleached, washed airplane linen attached with pva emulsion (heat activated) to a rag board window mat. The linen provided an aesthetically pleasing background layer for viewing the scroll fragment. Below this were two layers of add free blotter as a cellulosic relative humidity buffer. A silica gel tile would provide even greater buffering capacity, however, loose silica gel should be avoided due to the risk of stray gel in the package. An activated charcoal tile might be a useful addition to adsorb any volatile materials. The edges of this layered package were held together by two layers of J-lar acrylic tape along all four edge sides. Removal of the fragment from the package is fully possible.

The scrolls in their packages were displayed in exhibit cases buffered with silica get at an angle not exceeding 18 degrees. The shallow angle was intended to avoid potential pressure on brittle edge, by distributing the weight overall. The exhibit halls were all environmentally controlled and monitored. Lighting (max.3–4 footcandles) was viewer activated through infrared or button systems. The relative humidity was kept between 45–50%, with temperature 68–72 degrees F. Due to the package housing, the scrolls were quite easy to monitor during the course of the exhibit in terms of shifting, breakage, etc. Photographs and diagrams assisted in recalling details of staining, undulations, etc. This system or a variation thereof is being considered for long term storage.

Other possible options for mounting the fragments might have included the following, however were not considered appropriate in this context. Polyester encapsulation was not appropriate due to the delamination of some of the fragments, three-dimensionality of the support, aesthetic considerations and distracting glare. Hinging with Japanese tissue or a related material was not used to avoid any future need to remove the hinge in changing the housing. Straps or half moons did not seem aesthetically appropriate and in some cases would have been difficult to apply given the brittleness of some of the fragments.

Nineteenth Century Fine Art Prints on Parchment[edit | edit source]

(Jane Smith and Victoria Bunting)

History

The use of parchment as a substrate for fine art climaxed at the end of the nineteenth century in conjunction with the desire for objet de luxe reproductive prints in Europe and North America. In order to control the number of proofs per plate, regulating bodies, such as the Incorporated Printsellers' Association, were established in London. Prints produced under this Association's guidelines can be identified by the hand-written signatures of both the engraver and the painter below the image, and the absence of any engraved inscription except for the publication line. Artist's proofs always had the Printsellers' Association stamp in the lower left hand corner. (An Alphabetical Listing of Engravings at the Office of the Printsellers' Association, London, from 1892–1911 Inclusive, 1912).

Of the tens of thousands of prints pulled from a typical plate, 125–250 of these were apparently artists proofs on parchment (An ... Printsellers' Association ... 1912). A variety of subject matter was represented in parchment prints of the late nineteenth century. Landscape images were commonly reproduced as prints on parchment at this time, as were dramatic scenes after Pre-Raphaelite paintings by William Holman-Hunt, Sir Lawrence Alma Tadema and others. Nineteenth century de luxe edition reproductive prints are often on a split skin substrate and can measure from 45–55 cm by 65–80 cm.

Since the ink is never absorbed into the skin but rather, spreads under the pressure of the press, the print will have a gorgeous velvety texture, which may be easily disturbed during conservation treatment. Treatment options for these objects are limited because of the fragile surfaces of the ink, which are easily abraded and which may detach if the supports are flexed too much, and because of the inherent weakness of split skins.

The modest pressure used during printing may help to explain the faint or even absent platemark of many prints. Jenkins suggests that the platemark could be lost in the pressing after the printing. The platemark could also be lost in the mounting of the parchment to the backing board in preparation for framing.

Since these prints on parchment were deluxe versions of printed editions on paper, they also were expected to be relatively flat. These prints may be found glued down to a rigid support which is quite possibly their original mount. Catalogues of the period note that publishing companies such as the Fine Arts Society would do mounting of prints for the buyer (Sparrow, 1926; McIntosh-Patrick, 1993). The original mount may be of poor quality materials which should be removed. The consequences of restraining skin, which has its own inclinations to move, accompanied with prolonged exposure to fluctuating relative humidity and temperatures, can be damaging to prints. Problems include cockling, splitting, tightening like a drum, and pulling away from the support.

Treatment

  • Removal of Adhered Matting and Mounting Boards
The brittle and broken backing board and window mat may be removed from the sheet of parchment mechanically, dry with spatulas and with Methyl cellulose (A4M high DP) poultices if the adhesive is water soluble. (See Spot Tests.) While this technique may remove some of the adhesive, there still may be residual adhesive in and on the skin. Although parchment is much more resistant to abrasion than is paper, it is still possible to abrade its surface, especially on the degraded edges.
Thin accretions of adhesive and mounting materials may be removed by swabbing with saliva and blotting the surface dry. If moisture in any form is applied, deformation where hot animal glue was applied originally in the mounting process may become more pronounced.
To provide access to the inside of folded edges, the crease of the fold may be swabbed with undiluted absolute ethanol to gradually relax it. One consequence of this process is that tidelines may result in discoloured skins. The tide lines may be reduced by feathering the hard edge with ethanol.
  • Surface Cleaning and Disinfecting Mold Covered Areas
Superficial surface grime and surface mould may be removed by swabbing with absolute ethanol in non -image areas only. Eraser cleaning as applied in paper conservation may be used for non-image areas. In image areas, loosely adhered accretions and mould may be picked up with a kneaded eraser with the aid of the stereo binocular microscope. Tenacious accretions such as dots of paint can be broken up with the point of a scalpel and the fragments dusted off by brush or air from a photography bulb/hurricane blower.
Review of current knowledge and treatment options, offer no acceptable method for minimizing the staining caused by mould and matting materials
  • Retensioning
In retensioning parchments the surface characteristics of the ink and the image dimensions must be carefully maintained. The precise square shape of the image is important in keeping with the pristine surface and aesthetic qualities considered desirable in prints from this period. Breaks and thinned areas already present in the skins must not be accentuated.
There are numerous ways to retension parchment These prints on parchment may withstand only minimal tensioning. One method to apply minimal tensioning is as follows. Construct a wooden strainer of dimensions two to three inches larger than the object. Hammer galvanized nails around perimeter on one side of strainer at one inch intervals, leaving heads protruding. Make a grid pattern using fishing line wrapped around the nail heads. This will be used to support the object in the humidity chamber. Elastics are used to attach bulldog clips to each nail. The clips should be padded with blotters, felts, Pellon, etc. to protect the parchment from indentations. These clips will be used to tension the parchment once it is humidified by adjusting the elastics around the nails. During humidification the parchment may be held with a few bulldog clips on each side to prevent curling or extreme distortions. After sufficient humidification, additional clips are applied and the tension is adjusted using the elastics. After a few hours, the parchment may be removed from the strainer and placed between blotters, felts and plate glass. If appropriate, more weight may be added. In most cases complete flatness may impossible to achieve without risk of damage to the image or distortion of dimensions. (Jane Smith and Victoria Bunting)

References

An Alphabetical Listing of Engravings at the Office of the Printsellers' Association, London, from 1892–1911 Inclusive. 1912. London: Printed for the Incorporated Printsellers' Association.
Sparrow, W.S. 1926. A Book of British Etching from Francis Barlow to Francis Seymour Haden. London: John Lane The Bodley Head Limited.
Personal correspondence, 1993, Mr. Andrew Macintosh-Patrick, Fine Arts Society Archives, 148 Bond Street, London W1Y 0JT, England

U.S. Public Laws: Record Copies on Parchment[edit | edit source]

(Catherine Nicholson)

Following practices established in England, the official record copies of U.S. public laws were engrossed, that is, hand-written in a formal calligraphic hand, on parchment supports. The initial words or lines of the text would be written with larger, thicker, thus “engrossed” letters, built up of multiple parallel pen lines with the space between parallel lines hatched or filled in solidly with ink. As early as 1802, the engrossed initial words were printed by letter press on the parchment, with the remainder of text handwritten in iron gall ink on a parchment support, generally unsplit.

Continuing into the first quarter of the nineteenth century the parchment supports were large, up to about 30 by 34 inches. While laws of shorter length were written on one side, generally the toothier flesh side of individual parchment leaves, longer laws were written front to back, with text running from top to bottom on the recto and then from bottom to top on the verso. For longer texts, faint pencil guidelines were made, sometimes between holes pricked in the side margins. The practice of writing from bottom to top on the verso indicates that initially the separate leaves were joined together along the top edge, a practice common in English public records. The U.S. Constitution similarly has a set of vertical slits in the top margin of each parchment leaf, with faint blue coloration on the split edges apparently from ribbon used to hold the several pages together. (They are however only written on the recto.)

Until the late nineteenth century, the Constitution is known to have been rolled, and for some period of time the rolled parchment leaves were stored in a tin cylinder. All the large parchment public laws were probably originally stored rolled. The office entrusted with their custody during the nineteenth and early twentieth century was called the Bureau of Rolls at the State Department. Physical evidence of rolled storage remains in parallel horizontal ridges or creases, and in patterns of stains that repeat along the length of a parchment leaf. They may later have been bound into structures with leather-covered spines, possibly in the late nineteenth century, as small remnants of brown leather were found glued along the upper edge of one early public law. In 1926 the Government Printing Office bindery devised a postbound structure for the large early public laws, which continues in use today. The shorter individual leaves were stitched and glued with animal glue along their top edges to buckram tabs. These buckram tabs and the top edges of the longer parchment leaves were then sewn together onto a buckram tab into signatures of about ten leaves. Each signature had a reinforced buckram top edge with grommet holes held into a large locked post bound structure, measuring 33 × 40 inches closed. Several signatures of Public Laws are grouped in a post binding by session of Congress, arranged by date of approval and numbered sequentially.

In 1824, smaller parchment leaves ca. 15 × 22 inches began to be used for public laws. The parchment was split, making it thinner. Faint blue lining served as a guide in writing the manuscript text, below the engrossed initial lines printed by copperplate engraving. Text was generally written only on the recto. By the middle of the century the use of red and/or blue ink border lines in the margins around the text became common. The parchment leaves were sewn along the left edge into leather bindings arranged by session of Congress. In 1893, the size of the parchment leaves decreased even further to ca. 10 × 15, because the text was now printed on the recto only within a border line of double red lines. The leaves were bound along the left edge into volumes.

In 1920, the use of parchment for record copies of laws was discontinued, and a high quality heavy weight off-white wove paper was introduced. Text was printed within a red line border in the margins, with original pen and ink signatures on the final page.

The National Archives has had a practice of making “red line” copies of public laws upon request which can on first glance be confused with the originals, as the red line border paper used is the same used for printing public laws. The copies are produced on a xerographic copier and can be distinguished from originals on close examination.

Though they are not public laws, the ratification copies of the Constitution and Bill of Rights were also executed on parchment supports. Ratification copies, which were sent to each state for approval, are in addition to the official record copy retained by the U.S. government, so more than a dozen copies were originally created. Ratification copies typically show evidence of having been folded up for transport to the states, with an endorsement or address written on the exterior of the folded up document.

The Declaration of Independence[edit | edit source]

(Elissa O'Loughlin)

The Declaration of Independence, the Constitution (five pages) and the Bill of Rights were sealed in glass and bronze cases in 1951–52. The work was done by the National Bureau of Standards under contract to the Library of Congress. The parchments are held by compression on several sheets of a high alpha-cellulose paper within the cases which contain humidified helium. Evelyn Erlich and George Stout treated the Declaration for the Library of Congress in 1942. The upper right corner had become detached in part due to the uncontrolled exhibition environment at the Library. A circular loss about 1/2” in diameter above the letter “m” in “America” was inserted with new parchment. Minor tears and small losses were mended with Japanese paper and wheat starch paste, and pulp fills were made with Japanese paper fibers toned with Winsor and Newton watercolors. For his work on the Declaration, George Stout was named “Honorary Consultant in Parchments” by Archibald MacLeish, then Librarian of Congress.

Verner Clapp asserted (Special Libraries, Dec, 1971) that the reason for the poor condition of the Declaration was that the parchment was “not even an excellent sheet of parchment to begin with; apparently it was a home-made (colonial-made) piece of parchment found fairly quickly in the markets of Philadelphia.” Clapp's assertion has not been confirmed, and no source for the information is given in the article. However, there were parchment makers in Philadelphia and elsewhere in the colonies at the time of the Revolution. As early as 1748, David Hall (partne of Benjamin Franklin) advertised in the Philadelphia Gazette tht “very good” parchments were made locally by Joseph Wood were available for sale at the Post Office. Later, in the April 1779 edition of The New York Journal, Robert Wood advertised parchment made by himself for sale to stationers and large quantity users. Benjamin Franklin mentions a Robert Wood whose parchments were said to equal those of English import in quality. Other parchment makers were working in New York City and in Alexandria, Virginia in the latter part of the eighteenth century.

Storage and Display of Parchment[edit | edit source]

(Dr. Nathan Stolow)

The recently published studies<sp>1</sp> of the mechanical and biological properties of parchment and the recommendations under certain circumstances for reducing the accepted R.H. norm to the level of 30 &pm; 5% (albeit for modern vellum) is cause for concern, especially so for archival conservators and custodians of parchment documents, manuscripts and ancient artifacts of similar proteinaceous composition. For many years it had been established that old parchment, from the Dead Sea Scrolls to the U.S. Bill of Rights, required an ambient level of 50–60% to maintain suppleness, ease in handling, and geometric stability in display situations. The goal in climate controlled cases was to achieve constancy in RH. control over extended periods of time. Careful examination of the condition of parchment artifacts maintained in such cases showed that surface features were well preserved.

Thus, dimensional relationships and any distortions out-of-place remained fairly constant. Where documents were displayed flat, without appreciable restraints, it was determined that the parchment was sufficiently relaxed at the level of 50–60% RH. to justify the light restraints to anchor the document in position. Likewise, rare manuscripts exhibited at fixed (or occasionally variable openings) were less likely to be physically stressed when displayed at the recommended humidity levels.

My experience with parchment documents and manuscripts goes back some twenty-five years, particularly in the specialized field of controlled climate cases and exhibitions technology. I was responsible thus for the environmental and conservation standards for the display and travel of the Book of Kells and other manuscripts<sp>2</sp>; the Magna Carta (Brudenell/Perot); and more recently the Bill of Rights (Virginia)<sp>3</sp>. Summary descriptions of these projects with annotations relevant to ongoing study of the reactive properties of parchment are included here. In all instances the levels of R.H. in the 50–60% range were recommended by the institutions, archives, and consultant manuscript conservators themselves as conforming to past environmental history (display and storage) and desirable physical maintenance.

Kells and Other Irish Treasures

The exhibition, “Treasures of Early Irish Art: 1500 B.C. to 1500 A.D.,” included treasures from the Trinity College, Dublin; the Royal Irish Academy; and the National Museum of Ireland, and traveled from Dublin to the U.S.A. and to various U.S. major institutions from October 1977 to May 1979. Included in the exhibition were two volumes of the Book of Kells, the Book of Durrow and Dimma, Armagh, and Stowe manuscripts. This exhibition, in revised and reduced form, also traveled in Europe, 1980–83.

  • Required Environmental Standards
60 &pm; 2% RH.; 66–72°F.
  • Case Description
Externally back-lit acrylic cases with conditioned silica gel, and these display units (5) were housed in a large display structure with temperature control, moderate R.H. control, and various security alarms. Light levels were strictly controlled – ultraviolet free at 5 foot-candles at document surfaces.
  • Condition Monitoring
Daily R.H. and temperature monitoring by resident curator, and by consultant during site visits at each exhibition venue. Environmental reports sent regularly to Dr. Stolow and Irish authorities, and instantly evaluated for any possible remedial action, if required.
Photographs were taken initially of selected details of the Books of Kells and other documents and these areas are restudied at different times to determine if any changes were taking place. Observations of cockling and other surface defects particularly noted.
  • Comments
The level of 55–60% R.H. was rigorously maintained for the 18 month display period, and also in transit. Condition studies showed that the exhibited manuscripts and documents remained supple and flexible, and all decorative elements were well preserved.
  • Specialists Concerned and Acknowledgements
Dr. N. Stolow, Conservation Consultant; Anthony Cains, Manuscript Conservator, Trinity College, Dublin; Stuart O'Seanoir, Keeper of Manuscripts, Trinity College, Dublin.

Magna Carta - Brudenell/Perot

This version of the Magna Carta, dating to 1297, was purchased by Ross Perot of Dallas, Texas, in 1984 from the Brudenell Estate in Great Britain. The parchment document measures 14 1/2” wide by 17 3/4” long, is written in Latin, and has an attached seal. After conservation treatment by Don Etherington and assisted by James Stroud, it was prepared for travel in a specially designed climate controlled case and outer security container by Nathan Stolow. The overall exhibition design was executed by Staples and Charles of Washington, D.C. The itinerary covered the period 1985–86, including showings in Washington, D.C.; Philadelphia, Pennsylvania; Dallas and Austin, Texas; and Boston, Massachusetts.

  • Required Environmental Standards
52 &pm; 2% R.H., 68–74°F. 5 foot-candles illumination ultraviolet free, vibration and shock protection in transit; nitrogen environment; pollution control.
  • Case Description and Condition Monitoring
At the end of the tour the document was exhibited again in the Rotunda of the National Archives. In 1990, Dr. Stolow redesigned the climate controlled case, installing a permanent one fabricated in stainless steel and housing the document on a special platform with securing devices modified by Don Etherington. The R.H. control was achieved by preconditioned silica gel maintaining a consistent level of 52 &pm; 2% at ambient Rotunda temperatures. This climate and light controlled case was fitted with various probes, including that for R.H. and temperature (Vaisala Hygrometer) reading the internal conditions from the externally rear-mounted meters. At the time of setting up, and on an annual basis, the case was charged with 99% nitrogen gas (at 52% R.H.), the level of residual oxygen determined on-stream with a Beckman oxygen monitoring device. To the extent possible, all internal materials used in the climate controlled case were deemed to be pollution free. To limit any residues of pollutants building up within the case, a quantity of activated carbon pellets was placed in a dust-free porous container under the platform of the displayed document alongside the silica gel bed.
In accordance with conservation standards, the light level infringing on the document was limited to 5 foot-candles, ultraviolet free. Outside of visiting hours, the display front of the Magna Carta installation was covered over with an opaque panel to limit the cumulated light exposure on the document. The external display housing in marble and anodized aluminum was designed by Staples and Charles. The external viewing glazing (spaced away from the climate control module) was of 11/4” Lexan, a material resistant to heavy blows, mechanical shock, and even bullet proof! This permanent installation remains as redesigned in 1990, and functions extremely well. Some typical environmental data, R.H. and temperature levels inside the case are given in Table I, and for the corresponding ambient conditions in the Rotunda external to the case in Table II.
  • Comments
The level of 52 &pm; 2% R.H. was very consistently maintained to date (6 years at least) at ambient conditions in the range of 68–74°F approximately. Periodic examinations at the “microdetail” level of selected areas and observations on the degree of suppleness of the document by Don Etherington confirmed that the display mode conditions were quite suitable for conservation purposes. An interesting proof of the stable surface configuration was obtained by taking periodic raking light macro-photos of selected readily repeatable areas under precisely controlled light angles. This was carried out by James Stroud and the author, and verified that the document was dimensionally stable and was in a suitable “equilibrium” state.
  • Specialists Concerned and Acknowledgements
Ross Perot, Bette Perot, Merv Stauffer, Dallas, Texas; Dr. Nathan Stolow, Conservation Consultant; Don Etherington, Manuscript Conservator; James Stroud, Manuscript Conservator; Linda Brown, Assistant Archivist, and Norvell Jones and her conservation staff members of the National Archives; Staples and Charles, Exhibition Designers, Washington, D.C.

The U.S. Bill of Rights (Virginia Version)

This parchment document is the original Virginia copy of the Bill of Rights, and was on loan by the Virginia State Library and Archives, Richmond, for the purpose of a 50 state national tour starting in Barre, Vermont, October 10, 1990, and ending in Richmond, Virginia, on the 200th anniversary of the U.S. Bill of Rights, December 15, 1991. The document is approximately 34” wide by 32” high (maximum dimensions). The preparation phase for the tour and the tour expenses themselves were underwritten by the Philip Morris Corporation. As Conservation Consultant, I was responsible for the design and construction of a climate controlled case to maintain constant R.H. levels, light protection, and to design as well a transportation container to travel the environmental module from state to state. The overall exhibition concept was designed by Associates and Ferren of Long Island, N.Y., who worked closely with me to ensure that my controlled climate case meshed in with the “high tech” devices used for the display mode. A special mobile track system was used underneath the public waiting rooms (above) to bring the document and its case by an elevating device into view. There were two such elevator shafts for viewing in alternate stations. The glazing at the viewing platforms was of bullet-proof 11/4” thick Lexan.

As can be imagined, a 50 state tour with up-to-date visual devices, video screens, posters, etc., involved a veritable army of staff and personnel ranging from technical and conservation experts to security personnel, and all sorts of installers and movers.

Prior to each state's public opening, the document was checked, as was the environmental monitoring system. This consisted of a Vaisala Hygrometer (R.H. and temperature sensors) hooked up to computers in an equipment trailer nearby. Readouts of R.H. and temperature could be ascertained in a variety of formats at any time (during and outside of exhibition hours).

  • Case Description and Condition Monitoring
Silica gel conditioned to 50–54% RH. was used for maintaining the R.H. levels to an achievable range of 51–55% R.H. throughout the tour. The stainless steel case with 1/2” thick acrylic glazing was periodically purged with nitrogen gas to reduce the oxygen level to 1% or less. Pollution control devices were also utilized as described earlier in the Magna Carta project. The ambient temperatures were maintained by a separate air conditioning system keeping the exhibition case to within the range of 68–72$ F.
Periodic inspections of the document by myself, Don Etherington, and Dr. Manarin (of the Virginia State Library and Archives) confirmed the efficacy of the R.H. levels in maintaining the Bill of Rights parchment in a supple and relaxed state throughout the tour.
  • Comments
The Bill of Rights was adequately conserved and protected at the R.H. level of 51–55% R.H. with light levels controlled to 5 foot-candles. The constancy in dimension and configuration of the Bill of Rights was attributed to the controlled case environment.
  • Specialists Concerned and Acknowledgements
Dr. Louis Manarin, State Archivist, Virginia State Library and Archives; Dr. Nathan Stolow, Conservation Consultant; Bran Ferren, Associates and Ferren, Designers and Staff Engineers; Don Etherington, Manuscript and Book Conservator.
Also work credited in the following press releases:
  • October 6, 1990: “200th Anniversary of the Bill of Rights. Preservation on Tour: Two Conservators and a Design Wizard Share Preservation Techniques for the Bill of Rights.” Philip Morris Companies, Inc., New York, N.Y., 6 pp.
  • April 24, 1985: “1297 Magna Carta on Loan to National Archives.” National Archives, Washington, D.C., 2 pp.

References and Notes

Hansen, E. F., S. N. Lee and H. Sobel. “The effects of relative humidity on some physical properties of modern vellum; implications for the optimum relative humidity for the display and storage of parchment.” Journal of the American Institute for Conservation 31, no. 3 (1992): 325–342.

Irish Treasures Exhibition and Kells Books, etc., described in Stolow, Nathan, Conservation and Exhibitions, London: Butterworths, 1987, pp. 68–69, 205, 210–211.

Descriptions of my consultancy work on the Magna Carta and Bill of Rights projects were included in a paper given to the Virginia Conservation Association meeting in Richmond, VA, September 26, 1991: “Microclimate Case Technology for the Virginia Bill of Rights and for the Magna Carta.”

References[edit | edit source]

Bibliography[edit | edit source]

The Marburg Parchment Colloquium (20-22 September, 1987)[edit | edit source]

Geschichte und Verwendung

Rueck, Peter. “Zum Stand der hilfswissenschaftlichen Pergamentforschung,” Ryder, Michael L. “The Biology and History of Parchment”
Haran, Menahem. “Technological Heritage in the Preparation of Skins for Biblical Texts in Medieval Oriental Jewry,”
Endress, Gerhard. “Pergament in der Codicologie des islamisch-arabischen Mittelalters,”
di Majo, Anna; Federici, Carlo and Marco Palma. “Die Tierhautbestimmung des Pergaments der italienischen Chartae Latinae Antiquiores,”
Brown, Michelle P. “Continental Symptoms in Insular Codicology: Historical Perspectives,”
Eisenlohr, Erika. “Die Pergamente der St. Galler Urkunden: Ein praktischer Versuch zur Bestimmung von Tierhauten,”
Bischoff, Frank M. “Pergamentdicken im Evangeliar Heinrichs des Loewen und anderen Helmarshausener Evangeliaren des 12 Jahrhunderts,”
Gullick, Michael. “From Parchmenter to Scribe: Some Observations on the Mansfacture and Preparation of Medieval Parchment Based Upon a Review of the Literary Evidence,”
von Scarpatetti, Beat M. “25 Scriptoren und Maler auf 150 Folia Pergaments. Ein Schweizer Erfahrungsbericht 1986/7,”

Structur des Pergaments

Moog, Gerhard. “Haeute und Felle zur Pergamentherstellung. Eine Betrachtung histologischer Merkmale als Hilfe bei der Zuordnung von Pergamenten zum Ausgangsmaterial,”
Stachelberger, Herbert; Banik, Gerhard and Anna Haberditzl. “Naturwissenschaftliche Untersuchungen zum Pergament Methoden und Probleme,”
Chahine, Claire. “Travaux Realisés en France dans la Domaine de Parchemin,”
Tanasi, Maria T.; Impagliazzo, Giancarlo and Daniele Ruggiero. “Une Approche Préliminaire à la Caraterisation du Parchemin,”
Reed, Ronald. “Some Thoughts on the Treatment of Parchment with Aldehydes,”
Heidemann, Eckhart “Einige Bemerkungen ueber die Eigenschaften von Pergament aus der Sicht der Lederwirtschaft,”

Restaurierung und Konservierung

Waechter, Wolfgang. “Pergament: Die gegenwaertig praktizierten restauratorischen Methoden und ihre Beziehung zum Erkenntnisstand,”
Ritterpusch, Ludwig. “Pergament-Restaurierung,”
Martinovsky, Ivan. “Die neuesten tschechoslowakischen Erfahrungen auf dem Gebiet der Pergamentrestaurierung,”
Rosa, Halina and A.B. Strzelczyk. “Parchment - Report on Conservation and Scientific Methods Developed in the Laboratory of Paper and Leather Conservation at the Nicolaus Copernicus University, Torun, Poland,”
Fuchs, Robert. “Des Widerspenstigen Zaehmung [Pergament in Strucktur und Geschichte],”
Waechter, Otto. “Das Pergament als Biltraeger. Ein konservatorischer Aspekt,”
Dreibholz, Ursula. “Der Fund von Sanaa. Fruehislamische Handschriften auf Pergament,”
Lokanadam, B. “Parchment in India - Some Observations,”
Schmitzer, Wemer. “Pergament: Das Material fuer Schattenspielfiguren, ihre Herstellung und ihre Restaurierung,”

Perg Amentherstellung Heute

Visscher, J. “Parchment: Properties and Varieties Manufactured at William Cowley Parchment Works, Newport Pagnell, Great Britain,”
Wildbrett, Manfred and Edith Wildbrett. “Hautpergamentein Naturprodukt von erlesener Schoenheit,”
Vorst, Benjamin. “Mysterious Vellum,”
de Groot, Zeger H. “Die Herstellung von Goldschlaegerhaut, transparentem und gespaltenem Pergament,”
Esteves, Lilia M de A.A. and Luisa M.P.P. Alves. “Note sur l'Étude du Parchemin au Portugal: Sa Fabrication,”
Ameneiro, Rony. “From Banjos to Parchment,”

Ikonographie und Bibliographie

Janzen, Stephan. “Bilder zur Pergamentherstellung,”
Institut fuer Historische Hilswissenschaften and Stephen Janzen. “Pergamentbibliographie,”
Verzeichnis Heutiger Pergamenthersteller.

Personal Correspondence

McIntosh Patrick, A. 1993. Personal correspondence.
Morrow, G. 1993. Personal communication.
Young, G. 1993. Personal communication.

History of This Page[edit | edit source]

This page was created in April 2022 when the Parchment page was updated.

Book and Paper Group Wiki
Wiki Editor Resources

Contributors' Toolbox · Reference and Bibliography Protocols · Accessing Conservation Literature (AIC) · Help Wanted · Template for New Page

Materials and Tips

Annual Meeting Tips Sessions · Materials, Equipment, and Tools · Adhesives · Adhesive Recipes and Tips · Leather Research · Conservation Supply Sources (AIC) · Gels, Thickeners, and Viscosity Modifiers (ECPN)

Examination, Documentation, and Analysis

Glossary of Terms · Visual Examination · Written Documentation · Documentation of Books · Watermarks · Fiber Identification · Spot Tests · Analytical Techniques (PSG) · Non-destructive Testing and Instrumental Analysis (PMG) · Oddy Tests (R&A) · Microchemical Testing (R&A)

Preservation

Selection for Preservation · Exhibition, Supports, and Transport · Choosing Materials for Storage, Exhibition & Transport (AIC) · Imaging and Digitization · Housings · Matting and Framing · Encapsulation · Collection Care (AIC) · Integrated Pest Management (AIC) · Environmental Guidelines (AIC) · Environmental Monitoring (AIC) · Agents of Deterioration (AIC) · Light (AIC) · Pollutants (AIC)

Disaster Recovery

Emergency Preparedness & Response (AIC) · Stabilizing Wet Paper (AIC) · Stabilizing Wet Books (AIC) · Stabilizing Wet Skin and Leather (AIC) · Mold

Conservation History and Ethics

AIC Code of Ethics and Guidelines for Practice · Culturally Sensitive Treatment · Conservation Ethics (AIC) · Sustainable Practices (AIC) · History of Conservation and Conservators (AIC) · History of the BPG Wiki

Book Conservation Topics
Structural Elements of the Book

Endpapers · Endbands · Sewing and Leaf Attachment · Book Boards · Board Attachment · Book Decoration · Fastenings and Furniture

Treatment Techniques

Washing of Books · Alkalinization of Books · Leaf Attachment and Sewing Repair · Board Reattachment · Use of Leather in Book Conservation

Covering Materials

Animal Skin and Leather · Cloth Bookbinding · Paper Bookbinding · Parchment Bookbinding

Bookbinding Traditions

Bookbinding Traditions by Region or Culture · East Asian Book Formats · Ethiopian Bindings · Greek-Style Bindings · Western African Books and Manuscripts

Specialized Formats

Scrapbooks · Atlases, Foldouts, and Guarded Structures

Circulating Collections

Circulating Collections · Case Binding