User:Sblais/Starch Adhesives

THIS ENTRY IS A DRAFT

Conservation Specialties

Conservation Specialties Analysis and Imaging Preventive Care Education and Professional Development Workplace Practices About Conservation Lexicon

• Book and Paper

Group

• Book and Paper Group

Section

• Tools, Equipment, Materials, and Supplies

This page discusses the topic of starch adhesives.

Wiki Compilers:
Wiki Contributors: Sandrine Blais, your name could be here

Copyright 2026. The AIC Wiki is a publication of the American Institute for Conservation (AIC). It is published as a convenience for the members of AIC. Publication does not endorse nor recommend any treatments, methods, or techniques described herein. Information on researching with and citing the wiki can be found on the Reference and Bibliography Protocols page.

Cite this page:

American Institute for Conservation (AIC). "User:Sblais/Starch Adhesives." AIC Wiki. February 3, 2026. https://www.conservation-wiki.com/wiki/User:Sblais/Starch_Adhesives.

Starch adhesives

The adhesive qualities of vegetable starches were recognized in early history. The first recorded use of a starch adhesive dates from the first century A.D. in a description of papyrus manufacture by Pliny the Elder using a paste made from wheat flour. Starch adhesives are now used throughout the world in numerous industrial applications such as papermaking and textile manufacture. Western paper conservation use has been influenced by the East Asian scroll mounting tradition.

Source

Starch adhesives are derived from the roots and seeds of plants such as corn, potatoes, rice, and wheat. The last two are commonly used in conservation. The plant material is processed by a variety of means including treatment with acids, bases, enzymes, and oxidizers. These processes modify a starch's viscosity and "retrogradation" (i.e., stiffening). Depending on the starch type, and the processing method, a vast range of viscosities and adhesive strengths can be produced.

Chemical and physical properties

Starches are naturally occurring polymers of glucose. With the empirical formula of (C₆H₁₀O₅)n, where the exact value of n is unknown. Starch has a more intricate structure than cellulose because its molecules have two distinct areas: 75% has a branched amylopectin molecular structure and 25% has a linear amylose molecular structure. The exact percentages of amylose and amylopectin for each starch is largely responsible for its working properties.

"Amylose and amylopectin have different properties, both as dry films and in solution. The highly regular linear structure of amylose allows it to dry from solution to form strong films...Amylopectin, being more amorphous, forms weak films". Wheat starch contains 18-27% amylose while rice starch contains approximately 17-19% amylose. An AYTEX-P wheat starch representative stated that their wheat starch consistently has an amylose fraction of 25% and that American wheat starches have a consistent range from 23-25%. The 18-27% amylose range reflects world-wide variation. European or Japanese amylose ranges may be different from American wheat percentages. Vincent Daniels measured the percentage of amylose in aged Japanese paste, reporting that at two years of aging the amylose is approximately 19%, at four years it is approximately 22%, and at fifteen years it is approximately 24%.

During paste-making the amylose and amylopectin areas of the molecule behave very differently. The amylose fraction is responsible for the internal strength of a starch, many of its working properties, and for its degree of stiffening upon cooling. Thus, the amylose is responsible for gelatinization.

Identification

Amylose stains intensely blue in the presence of iodine. Amylopectin stains red to purple. Wheat starch pastes stain blue/purple with iodine.

Physical form

Vegetable starches are white powders consisting of tiny granules that vary among starch types in form, size, range of size, and marking. Granule sizes range from less than 0.001 mm to 0.15 mm of diameter. The granules are crystalline.

pH

The pH of starches and starch products is not reliably measured by indicator papers, but should be tested with the pH meter. During commercial manufacture, pH is usually kept between 4.0 and 7.5. In the lab, the pH of either the starch-water slurry or the cooked paste can be adjusted easily. Some conservators use alkaline water to prepare pastes that can serve a dual purpose of adhesion and assistance in alkalization/neutralization (e.g., lining). High pH (above 7.5) favors ready dispersal and slow settling of the granules. However, above pH 7.5 discoloration may result when the paste film dries. Variations of pH among starch granules or uneven dispersion of any pH adjustor can negatively affect a paste's appearance and performance.

Possible additives

None.

Health hazards

No health hazards. However, as with all fine powders, a dust mask should be worn by those sensitive to airborne irritants.

Storage/shelf life

Starch powder can be stored indefinitely if kept in an air-tight container in a cool place. Starch pastes are subject to fairly rapid biological attack within a few days of preparation. The deterioration can be slowed somewhat by the addition of a fungicide, but it is recommended that paste be made fresh on a weekly basis to avoid adhesive failure. Because fungicides can cause yellowing of paper over time some conservators avoid mixing a fungicide into their paste by attaching a fungicide-soaked cotton ball or blotter onto the storage container lid. Some conservators do not use any fungicide, but make fresh paste frequently. Others prefer to store their paste in a refrigerator; however, paste "should not be kept at the low temperature of a domestic refrigerator (4°C/39.2°F) as it will become granular and lose adhesive qualities.". East Asian and some Western conservators store their paste under water which is changed daily. Any blending, stirring, or straining of a starch paste before storage may result in more mold spores being introduced into the paste, making it spoil faster.

Preparation

Pastes for use in conservation are generally prepared by first soaking the starch in water and then cooking it in additional water. Longer cooking time, higher temperatures, and agitation promote the necessary bursting of the granules. Each starch has its characteristic gelatinization range which extends from approximately 55-80°F (131-176°F). Cooking technique, as well as origin of the starch, affect the characteristics of the resulting adhesive. (See discussion of preparation methods below)

Solubility

Starches do not form true solutions, but rather colloidal dispersions. Cooked starch paste is a mixture of greatly swollen granules, fragments of granules that have burst open, and dissolved starch. Starches swell in cold water and are partially dispersed in hot water. Starches are broken down with starch specific enzymes and are soluble in 2,1 n methyl pyrrolidone.

Aging characteristics

Reversibility

Pure starch adhesives remain indefinitely swellable in water and exhibit good reversibility. Starch adhesives of unknown quality found on objects being treated might require starch specific enzymes for their removal. Reversibility may be difficult with thick paste layers; enzymes or mechanical removal may be necessary.

"Amylose has been shown to degrade by photo-oxidation and hydrolysis reactions on exposure to ultraviolet, resulting in breaking of the chain and production of organic acids".

Appearance

Good quality starch adhesives should not undergo any color change after aging. As encountered by conservators on previously treated objects, appearances can range from invisible to continuous coatings of slightly gray or yellow translucence to crumbly, opaque surfaces in tones ranging from white to gray to yellow/tan.

Relative Strength

Some conservators feel that dried starch paste films gradually become brittle.

Biological Attack

Starch adhesives are also subject to attack by insects, rodents, and enzymes.

Wheat Starch Paste

Main article: Wheat Starch Paste

Wheat starch paste is very commonly used in book and paper conservation.

Rice Starch Paste

This is generally considered to be a weaker adhesive than wheat starch paste. However, it is uncertain what the amylose content is for American and European rice starches. Differing amylose percentages and individual working habits of conservators may contribute to contradictory statements regarding properties of rice versus wheat starches. Possible uses are in situations where wheat starch paste would be too strong. Some conservators believe that rice starch paste is not as likely to cause a grayish haze or stain when it dries.

Source

The starch granules are separated from flour or kernels by chemical softening and steeping and then further processed by dewatering and drying, similar to wheat starch processing.

Chemical and Physical Properties

Rice starch has less retrogradation than wheat starch paste.

Identification

The granules are polygonal in shape and are the smallest of any common starch, between 4 and 8 microns in diameter. Some conservators believe that this property makes rice starch paste smoother than wheat starch paste.

Physical Form

Available as a white powder.

Preparation

Generally prepared by soaking the dry powder in water, followed by cooking in additional water. The gelatinization temperature is usually somewhat higher than that of other starches, (about 68-78°C) (154-172°F).

pH

Usually about 8 since most commercial preparations use alkaline steeping.

Solubility

Some conservators feel rice starch adhesives swell and release sooner than wheat starch. This property can be utilized in mending with wheat starch paste followed by lining with rice starch. This could allow the lining to be applied and possibly removed without disturbing the tear repairs.

Storage/Shelf Life

Waxy or glutenous rice starch has great stability against water separation from the paste when stored cold.

Preparation

All recipes use distilled or deionized water.

Rice Starch mixed with PVOH can be refrigerated for long periods of time. It makes a very strong paste for mending and holds well in mending tears before an overall lining.

For recipes using an electric saucepan or a microwave oven see wheat starch paste recipes #5 and #6.

Rice Starch Paste #1 (Metropolitan Museum of Art)

Combine 52 g of rice starch and 364 ml water in a closed container and shake. Allow to soak at least one hour. Cook starch and water in an enamel pot, with constant stirring, until it boils. (At this point, 5 g laboratory gelatine which has been heated in 50 ml water until dissolved may be stirred in until it boils again.) Continue stirring until paste becomes quite thick. One may, with good ventilation, stir in fungicide (5 ml of a saturated solution of thymol in methanol). Another option is the addition of 1 g of calcium carbonate in 5 ml of water. Remove from heat. Pour into a jar, allow to cool somewhat, and cap.

Rice Starch Paste #2 (Katherine Eirk)

1. Stir 3/4 tsp. of methyl cellulose into 25 ml of water and let stand 20 minutes. Add 25 ml water and stir and let stand another 20 minutes. Add another 25 ml water, stir.
2. Place 1 1/2 cup of rice-starch powder in top section of a double boiler. Add small amount of the 2 cups of required water, and stir to a smooth paste. Bring water in lower half of the double boiler to boil. Boil the remaining water in a separate glass plan. Assemble the double boiler. While constantly stirring the starch mixture, slowly add the boiling distilled water. Cook and stir the paste until it becomes translucent (25-40 minutes). Remove the top section of the double boiler and cover. Allow the paste to cool to room temperature. When the paste is cool, add the prepared methyl cellulose jelly.
3. Dissolve 1/3 tsp ortho-phenylphenol in 5 tsp. grain alcohol. Stir the solution into the paste. Store the paste in a dark jar, unrefrigerated, but in a cool, dark place.
4. Dilute with water to consistency of heavy cream before use. (If paste seems lumpy, force through a strainer several times.) Undiluted paste will keep about two months.

Application

Rice starch paste is preferred when very flexible, smooth, and clean adhesion is essential. Rice paste is diluted and used to adhere tears from the front of an image through the media. After drying, the artifact is turned face down and reinforced on the back with wheat starch paste. It is also very successful for adhering fills or inserts.

Modified Starches

Dextrins are modified starches whose molecular structure has been changed through the use of heat, acid, alkali, or other catalytic conversions. Dextrins have been widely used for stamps, labels, and paper tapes, where the adhesive is moistened for application.

Source

Depending on the manufacturing process used, hydrolytic scission at either the 1-4 or 1-6 glucosidic links is responsible for the molecular modifications of the parent starch. Dextrins have been used as adhesives since the early nineteenth century. The earliest patent was issued in 1867. Starch was spread on iron pans and moistened with a dilute hydrochloric-nitric acid solution. After heating it was dried and used as a gum. Dextrins are often mixed with animal glue, gum arabic, or gum tragacanth. Frequently, blends of different dextrins are used and borax is a common additive to increase tack. There are three major types of dextrins: white, yellow, and British gums.

White dextrins are prepared by roasting at 107.2°C (225°F) in the presence of acid. These dextrins are then neutralized with some alkaline material such as ammonia. They are used in 50% concentrations. The color is white.

Yellow (or canary) dextrins are prepared by roasting starch with acidic catalysts at high temperature. Colors vary from light yellow to dark brown. Suitable concentrations are between 50-60%.

British gums are prepared by roasting starch up to 148.8°C (300°F) without using acid. These dextrins are usually dark colored and exhibit high solubility in warm water. They are used in concentrations of 10-35%.

Chemical and Physical Properties

Generally, dextrins are much more soluble in water than the source starch because processing has lowered the molecular weight. Dextrins also have a lower viscosity for an equal concentration as compared to starch. Dextrin properties are based on their method of preparation and the parent starch.

Possible Additives

Borax can be added to increase tack, rate of bonding, and to minimize wetting. Urea formaldehyde resin is used 5-15% for water resistance coatings.

Preparation

All recipes use distilled or deionized water.

Sodium Alginate Paste (Frances Prichett)

Sprinkle 1 g sodium alginate in 100 ml water and stir until dissolved. Add 10 g (used for repairs) or 5 g (for lining) arrowroot and heat in water bath until mixture is transparent. Cook for a further 15 minutes.

Sodium alginate granules can be added dry (a pinch) to existing paste to modify it.

Methyl Cellulose and Starch Paste

See also Lining

Application

Sodium alginate paste is a very strong "dry" adhesive and therefore useful for water-sensitive objects or when cockling must be avoided.(JR) Can be used to increase the "slip" of starch pastes (i.e., rice and starch), for instance when added to a lining paste.(PV)

Flour Pastes

These are encountered in former linings as historical adhesives. Contain brown chaff and particles. Not currently recommended for use.

Bibliography

Works cited in the text are below.

Browning, Bertie Lee. 1977. Analysis of Paper. 2nd ed. New York : Marcel Dekker, Inc.

Clapp, Anne E. 1987. Curatorial Care of Works of Art on Paper. Nick Lyons : New York, NY.

Daniels, Vincent. 1988. "A Study of the Properties of Aged Starch Paste (Furu-Nori)." The Conservation of Far Eastern Art - IIC Kyoto Preprints. John S. Mills, Perry Smith, and Kazuo Yamasaki, eds.

Horie, C. Velson. 1987. Materials for Conservation: Organic Consolidates. Adhesives. Coating. London: Butterworths & Co.

Kirby, Kenneth. 1965. "Vegetable Adhesives." Adhesion and Adhesives. R. Houwinte and G. Salomon, eds. London : Elswier, 1965.

Paper Conservation News. 1989. No. 49, Summery of a lecture given by D. Priest at the Institute of Paper Conservation. March.

Skeist, I., ed. Handbook of Adhesives. 1st and 2nd ed. Huntington, NY: Robert E. Kreiger Publishing Co., 1973/1977

TAPPI (Technical Association of the Pulp and Paper Industry). 1957. Starch and Starch Products in Paper Coating: Monograph 17." New York, NY : TAPPI.

Further reading

See also Adhesives § Bibliography

See also Wheat Starch Paste § Bibliography

Priest, Dereck. 1989. Paper Conservation News 49.

Summery of a lecture given by D. Priest at the Institute of Paper Conservation. Rutenberg, M.W. 1980. "Starch and Its Modifications." Handbook of Water Soluble Gums and Resins. New York, NY : McGraw-Hill Book Co.

Stirton, Laura, J. 1986. "Adhesion Variations in Wheat Starch Paste." University of Delaware and Winterthur Museum Art Conservation Program. Unpublished.

Swanson, John. 1972. Discussion on the Cooking of Starch Pastes. Washington, DC : Library of Congress. Transcribed by Barbara Gould, Restoration Office. Unpublished.

Van Steen, G.B. and L. Masschelein-Kleiner. 1980. "Modified Starch for Conservation Purposes." Studies in Conservation 25(2): 64-70.

Whistler, Roy Lester. 1964. Methods in Carbohydrate Chemistry, Volume 4: Starch. New York, NY : Academic Press.

Whistler, Roy Lester. and E.F. Paschall. 1965. Starch: Chemistry and Technology, Vols. 1 and 2. New York, NY : Academic Press.

Wills, Paul. 1984. "The Manufacture and Use of Japanese Wheat Starch Adhesive in the Treatment of Far Eastern Pictorial Art." In Adhesives and Consolidants: IIC Paris Conference Preprints. London, England : International Institute for Conservation. 123-126.

History of this page

This page was created in 2026 following the Adhesive page re-structuring. The information on this page originated in the Adhesive and Adhesive Recipes and Tips pages.

In 2016, the BPG Wiki Coordinators reformatted this chapter by removing the numbered outline format, combining the sections on "Materials and Treatment" and "Treatment Variations", renaming sections, and improving internal links. The "Glossary of Selected Terms" was moved to the BPG Glossary of Terms page. For more information on the reformatting campaign see the History of the BPG Wiki.

Prior to the creation of the BPG Wiki, this page was created in 1989 as Chapter 46: Adhesives of the 1989 edition of the Paper Conservation Catalog (PCC). For more information about the PCC see the History of the BPG Wiki.

Liaison: Catherine I. Maynor, Diane van der Reyden.

Compilers: Antoinette Dwan, Catherine Nicholson, Christine Smith with Sarah Bertalan, Janet English, Kimberly Schenck, Linda Stiber, Sarah Wagner, Sylvia Rodgers Albro.

Contributors: Cathy Baker, Dan Clement, Debora Mayer, Denise Thomas, Doris Hamburg, Francis Prichett, Frank Mowery, Janet Ruggles, Jill Sterrett, John Krill, Katherine Eirk, Lage Carlson, Lynne Gilliland, Martha M. Smith, Mary Baker, Paula Volent, T.K. McClintock, Tim Vitale