PMG Mending, Repair, and Filling
In progress: Seeking additional comments and images to develop this section
Photographic Materials Conservation Catalog
Mending, Repairing, and Filling
Date: Initiated September 2009
Contributors: Gary Albright, Heather Brown, Thomas M. Edmondson, Amanda Maloney, Laura Panadero, Stephanie Watkins
The Photographic Materials Conservation Catalog is created and maintained by the Photographic Materials Group of the American Institute for Conservation of Historic and Artistic Works as a convenience for the membership.The treatments, methods, or techniques described herein are provided for informational purposes. The reader assumes responsibility for any application results. Best professional judegment is necessary when using or interpreting information provided.
Purpose of Mending, Repairing, and Filling Photographic Materials
- Maximize the chemical and physical stability of the object.
- Minimize changes in the image, binder, and support.
- Provides basis for creating aesthetic reintegration of damaged photographic materials.
- Stabilize the object to facilitate display, digitization, access by researchers, and provide overall preservation of photographic materials.
Factors to Consider Before Mending, Repairing, or Filling
- Any attachment to the photograph needs to be of quality materials that will not chemically or physically alter the original material in accordance with AIC Code of Ethics.
- Materials and methods of attachment that can be safely reversed at a later date are preferred in accordance with AIC Code of Ethics.
- Replicating the color, reflectance (gloss or sheen), and surface texture of the original will visually minimize fill repairs on many photographic materials.
- Toning fills before insertion will create a more even tone and reduce the likelihood that colorant materials will imbed or wick into the original.
- Consider adhesive delivery techniques, flow, penetration, and molecule size before choosing an adhesive or application method.
- Historic photographic image layers may be weakened from age and situational damage. Consider the desired functional strength necessary of both adhesive and support material for any repair.
- Create a clean, reduced-dust environment in which to work. Many photographic material images are small. Small dust particles can be trapped within a mend, or scratch a surface while working.
- For sensitive photographic materials, consider wearing dust-free gloves. If necessary the gloves can be modified so only a few fingers and thumbs are exposed.
- Determine the appropriate degree of loss compensation based on the history and intended use of the photograph.
Effects of Mending, Repairing, and Filling on Photographic Materials
- Strengthen and stabilize the object for safe handling and display.
- Restore aesthetic continuity of the object for viewing.
- Stabilize current damage and decrease the likelihood of continued loss/damage.
Please see BPG's PCC Adhesive Recipes and Tips for additional and alternative information as many of the adhesives listed below are also used in paper conservation treatments.
- Photographic Grade, 250-300 Bloom often used
- Consider appropriate Bloom strength and concentration for individual application.
- Soaking the gelatin powder or grains for a half to a few hours in purified water helps shorten cooking time and creates an evenly distributed adhesive. Avoid boiling temperatures during cooking.
- Usually used warm. Can cool down quickly depending on time of year and interior temperature of working environment. Can be kept warm while working using a mug/cup warmer or hot plate on low temperature.
- Multiple reheating and cooling cycles can create adhesive darkening (yellowing) and higher likelihood of protein staining forming over time in paper-based photographic materials. To reduce this likelihood, good working practices include creating very small, fresh gelatin batches prior to working, or slowly reheating very small amounts taken from a larger recently made and gelled "mother batch" of gelatin that is kept refrigerated. Discard gelatin after use at end of each working session or each day for large projects.
- Can work well for relaxing and setting down lifting areas of emulsion around a crease, loss, or tear
Wheat and Rice Starch Pastes
- Good option when "strength", a strong bond, is required:
- Generally creates stronger adhesive bonds than cellulose ethers
- Mixing starch pastes with cellulose ethers can create even stronger, although sometimes less easily reversible, adhesive bonds. The extend of this result varies greatly upon the brands or types of adhesives used, the concentrations and proportion of each, and manner of application.
- Different types and brands of wheat and rice starch pastes can have different adhesive working properties such as wet surface attachment, tack, sheer, and strain. Pastes can all be made at different water:dry powder ratios. Pastes can be used thickly or thinned to any desired consistency before use as dictated by the photographic print being treated. Thicker paste applications will have less flex than thinly applied paste applications.
- Smoothness of paste is more likely to be achieved if the powder is soaked for half to a few hours before cooking, as with gelatin, and stirred continuously during cooking.
- Starch pastes can be made and thinned with purified water conditioned to the specific pH and conductivity levels of the photographic material being repaired if necessary to further reduce potential swelling of emulsion or substrate.
- Methyl cellulose (MC)
- Not as "wet" as paste, and may be a safer choice for moisture sensitive photographs
- Gives a longer working time and better "slip" than wheat starch paste
- Can be used in combination with wheat starch paste to get strength and slip
- Sodium Carboxymethylcellulose (SCMC or NaCMC)
- A longer chain molecule than methylcellulose and therefore gives a stronger bond than methylcellulose (Baker 2007)
- Hydroxypropyl cellulose (HPC)
- Several brands of HPC are available and have been used in conservation treatments over the decades.
- Klucel is a trademarked brand name of Ashland Chemical and is manufactured in various lengths and grades affecting viscosity. See: Klucel physical and chemical properties for more information.
- Klucel G (viscosity range 125-450 cps); Klucel M (viscosity range 4000-6500 cps)
- Non-tacky at high humidities; manufactured without plasticizers
- Klucel G, specifically, may discolor, yellowing slightly over time (Feller and Wilt, 1990), yet the level of "yellowness" may not be readily, visually noticeable in thin film applications such as used in mending or relaxing and setting down lifting areas of emulsion around a crease, loss, or tear.
- Klucel M is similar to Klucel G, but perceptively "stronger" adhesive due to increased chain length. M is significantly longer chain than G, and therefore can be used in higher percent concentrations if needed. Can be used as a mending paper adhesive, applied directly or pre-made and re-activated with alcohol (Adachi and Magee, 2017).
- Relatively "weak" adhesive
- Can be made with ethanol or isopropanol for photographic materials that are sensitive to water
- Can be set with low heat also
- For very weak and aged photographic emulsions, HPC films can be preferred over gelatin use for relaxing and setting down lifting areas of emulsion around a crease, loss, or tear
Plextol B 500
- Acrylate resin dispersion with water
- Can be used as heat-set when dry
- Comes in three different chain lengths with increasing strength: 50, 200 and 500
- Soluble in water and polar solvents
- Highly modifiable by combining chain lengths and solvent combinations
- Will yellow over time, especially Aquazol 50
Equipment and Materials: Considerations
- Round or flat shaped brushes are both useful shapes for adhesive applications.
- Brown synthetic hair brushes will show white and clear adhesives easier on the brush while working.
- Natural fiber brushes are best for using solvent-based adhesives. Test brush hairs against any organic solvents before working.
- Watercolor brushes have short handles, so are ideal for close work.
- Brush handles can be further shortened for work under the microscope.
- For large and over-size photographic materials, photographic and craft sponge brushes, commercial hardware paint sponges, and flat sponge-brushes are useful for applying adhesives evenly to large areas.
- This method tends to be used when other tools cannot reach a space or other methods cannot deliver enough ore evenly distributed adhesive, or when extensive areas need consolidation and overall consolidation is not feasible.
- Can be used to insert small amounts of adhesive between separated layers especially when large in size or long air pockets, such as blind voids.
- Small, thin needles are preferred.
- Even, slow pressure on the plunger is recommended as it is easy to "overfill" a void with too much adhesive.
- Light physical pressure is often needed to create a planar area after adhesive is inserted to avoid a lumpy appearance after drying.
- Best used for coloring and toning paper and pulp inserts before attaching to photographic materials.
- Advantages in toning with an airbrush include:
- Thinner, controlled applications that can lead to closer color matches (not overshooting color or tone)
- Thinner applications of color dry faster than brushing or floating methods, making coloring an insert a faster process.
- If the practitioner is skilled in using an airbrush, highlights, shadows, and even larger design elements can be reproduced on larger fills as necessary. Airbrush nozzles are too large to reproduce the small details within most photographic processes.
Ultrasonic delivery systems and nebulizers
- Water-based adhesives can be delivered in small vapor forms using ultrasonic or nebulizing systems.
- Usually a soft plastic container, such as poly(ethylene) (PET), is suggested.
- Wear appropriate personal protection equipment to protect lungs as vapor molecules are small.
- Standardized sizes of polyester webbing, blotters, and platens for use in flattening and drying can be pre-assembled for large jobs. Add desired weight amount.
Heat irons and warming plates
- For synthetic adhesives, the use of heating irons and warming plates may be necessary.
- Keep temperatures as low as possible to activate the adhesive.
- Apply heat through another material, such as silicone release paper. Wrapping the flathead of the heating tool saves time, but needs to be monitored closely for any debris it might attract.
- Prepare cooling/curing materials (glass and metal platens) for immediate flattening.
- Clean, bare hands are usually suitable. When mending sensitive photographic materials, however, sometimes gloves are preferred. Stretchy, lintless cotton photographic gloves with the forefinger and thumbs cut away are often ideal.
- Using a window "mask" or protective arm or hand barrier made of Mylar, board, or blotter can be used in conjunction with gloves if desired.
- Remoistenable tissue
- Heat-set tissue
- Teflon(TM), Poly(tetrafluoroethylene) or PTFE, tools shaped flat or rounded
- Plumber's tape
- Polyvinyl eraser blocks (such as Magic Rub or Staedlter Mars) inside a nylon stocking
- Barrier layers: Glassine, smooth-closed pore new polyester webbing, silicone release papers and films
Fillers and Additives
Microcellulose fibers with starch paste, methylcellulose, fish glue, Aquazol, or resins
- (+glass balloons, silicas, barium sulfate, titanium pigments, or kaolin)
Aquazol (various molecular weights) + inerts/dry pigments
- Flugger Acrylic Spackle (Denmark)
- Can be imprinted and burnished
- Modostuc Spackle (Italy)
- Crawford's Vinyl Spackling Paste (US)
- Beckers Latex Spackle (Sweden)
BEVA Gesso P
- Solvent based, BEVA adhesive
- Untoased or toasted
- With glass balloons
- With pigments
Useful Techniques for Photographic Materials
- For repairing cracking within prints, see the in-depth discussion under Consolidation and Flattening of Cracks.
- For materials that readily swell and you wish to use an aqueous adhesive, blotters can be dessicated in a microwave or warmed on a warming plate to pull out moisture prior to application against aqueous mend (Hugh Phibbs technique). Dessicated blotters pull out moisture more rapidly and reduce swelling and potential distortion than routine, room-temperature blotters.
- Using a flat small-headed tacking iron on low heat can help pre-flatten areas and set mend adhesives. Proceed cautiously as melting or rippling of the photographic material can occur if the temperature is too high or application time too long.
- Overall preliminary flattening can make alignment of tears easier before mending occurs. A dry mount press set at low heat can be useful in flattening overall. Pressures exerted by dry mount presses are variable. Overall flattening using a dry mount press after adhering mends on the back of a photographic print may leave distortions, or an impression of the mend in the photograph.
Mending A Fiber-Based Photograph
- Set up a work station with the photograph on non-woven polyester and blotter, or appropriate custom support.
- Gather all tools needed for the entire process before beginning: adhesive and a variety of brushes, water and/or solvent, spatula, tweezers, burnishing tool, squares of non-woven polyester and blotter, glass or acrylic plates and weights.
- Align the tear. Use small tools and gloves as necessary to bring the edges of the tear or break into alignment. Have an awareness of how the tear will fit together along its full length before applying any adhesive. Once the tear is aligned, weight both sides in place, and use magnification to tuck in any protruding paper fibers. Fine brushes, dental tools, and soft fine-tipped tweezers are especially good for this task.
- Begin applying adhesive to the exposed paper fibers along the tear. Apply adhesive to the underside of an overhanging flap, or the surface of the bottom ledge, taking care not to get any on the photograph surface. If working in sections, begin at the interior of the photograph and work outwards to the edge.
- Double check the tear for any protruding paper fibers and tuck them back into the seam. Do this with extreme care as the binder will be very soft from the adhesive and easily damaged.
- Firmly burnish the mended section through a piece of non-woven polyester and blotter, then place under a glass plate and weights until fully dry.
- Once the mend had dried it can be reinforced from the verso using thin strips of Japanese paper adhered with wheat starch paste or methylcellulose.
Cellulose Powder Fills
- Solka-flok is one brand of cellulose powder; 300 is the finest grade, 200 and 100 are more coarse.
- Cellulose powder is mixed with a solution of methylcellulose to produce a paste
- Cellulose powder can be "toasted" in a beaker on a hot plate to achieve various off-white and brown tones. This should be done with the dry powder, before mixing with methylcellulose. Wash after toasting to decrease the smell, sieve through Hollytex, let dry, and then grind in a mortar and pestle. You can break up any clumps on a micromesh.
- The paste can be pressed into small holes and losses with a micro spatula, and the surface smoothed with a Teflon tool
- Best for small losses where internal strength of the fill is not a concern
- When pulping fills for lost areas, overfill at center to counteract shrinkage and avoid forming a concave meniscus when dry. Premature smoothing will remove fill material from the damp center.
- Can dilute filling mixtures and dot on with a brush.
Toned and Colored Paper Fills
- Japanese papers or photo-safe Western papers may be dyed, painted, and finished to resemble a photographic surface, and used to fill large areas of loss
- Watercolors, colored pencil, and acrylic paints can all be used to impart color
- Watercolors: good for coloring or toning very absorbent papers. Papers can often be made more absorbent and receptive to watercolors by first soaking in hot water and avoiding surface manipulation until dry.
- Acrylics: work best when brush applied or smoothed with a brayer through Mylar. Floating paper on top of watered, exceedingly diluted acrylic paints tends to produce uneven coloration as the color media tends to separate and sink to the bottom of trays even when shallow.
- Colored pencil: good for fine lines and detail. Best applied on hard surfaces without much pressure to reduce paper indentation. Paper indentations created can sometimes be slightly mitigated if a water-based adhesive is used.
- Various surfacing materials can be used to adjust the gloss of toned papers:
- Acrylic gloss medium: applied thickly to the paper and placed face-down on Mylar or silicone-release Mylar, smoothed with a brayer, and allowed to dry against the Mylar. Tends to produce glossier surfaces than this same technique done with gelatin.
- Gum Arabic: when brush applied, creates a high-gloss surface with fine cracking an imperfections, closely resembling an aged albumen surface
- Gelatin(e): can be painted on for very subtle surface effects, or thick applications can be dried against Mylar to form a glossy film. Acrylic paints and gloss medium dried against Mylar will produce a glossier surface than will gelatin.
- Iridescent paints or pigments: when applied over toned layers can resemble mirrored photographic surfaces
Digitally Printed Fills
- Victoria Binder has published on a method for creating fills in Photoshop using a scan of the original photograph, and then using an inkjet printer to print out fills in a variety of tones on a paper with the desired gloss (fig. 1; Binder 2013).
Adachi, Michiko, and Catherine Magee. 2017. Captain American Encounters Klucel M, poster #22, Chicago, IL; Abstract in the 45th annual meeting Abstract Book, 93.
Albright, Gary. 2017. Using the Dry Mount Press in Conservation Treatments. Presentation and Handout at the AIC-PMG Winter meeting, Kansas City, MO.
Baker, Catherine. 2007. Sodium Carboxymethylcellulose (SCMC) Re-evaluated for Paper, Book, Papyrus, and Parchment Conservation. Book & Paper Group Annual 27. Washington D.C.: American Institute for Conservation.
Bernstein, James, Debra Evans, and Victoria Binder. 2018. Compensation for loss in the conservation of photographic materials workshop manual. Revised and updated. George Eastman House, Rochester, NY.
Binder, Victoria. 2013.Digital Fills for Photographs with Glossy Surfaces. Topics in Photographic Preservation 15. Washington D.C.: American Institute for Conservation, 363-370.
Feller, Robert L. and Myron Wilt. 1990. Evaluation of Conservation Ethers in Conservation, Research in Conservation Series, Los Angeles, CA: Getty Conservation Institute Publication