PMG Backing, Lining, and Mounting
In progress: Seeking additional comments and images to develop this section
Photographic Materials Conservation Catalog
Backing, Lining, and Mounting of Photographic Materials
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 benefit for the membership. The treatments, methods, or techniques described herein are provided for informational purposes. The reader assumes responsibility for any application results.
- 1 Purpose of Backing, Lining, and Mounting Photographic Materials
- 2 Definition of Terms
- 3 Factors to Consider Before Backing, Lining, or Mounting
- 4 Helpful Equipment and Materials and Considerations for Use
- 5 Techniques for Backing, Lining, or Mounting Photographic Materials
- 5.1 Re-moistenable tissue method
- 5.2 Dacron method (totally restrained on Dacron fabric on Formica, Plexiglas or glass support)
- 5.3 A modified Dacron technique (totally restrained on stretched Dacron support around a frame)
- 5.4 Suction table
- 5.5 Peripheral tension
- 5.6 Dry Mounting
- 6 Effects of Backing, Lining, and Mounting Photographic Materials
- 7 Resources and Further Reading
Purpose of Backing, Lining, and Mounting Photographic Materials
Attaching an additional support overall to a photographic material is considered when the original support materials have physically failed. An additional support might be added, or the photographic material removed from a secondary support and placed onto another secondary support.
The purpose of this section is to provide information to maximize the chemical and physical stability of photographic materials during and after the process while minimizing the likely changes in the image, binder, and support from the backing, lining, or mounting process.
Definition of Terms
The terms backing, lining, and mounting are often used interchangeably in speech. Yet all three have specific meanings within conservation specialty usage:
- Backing means to adhere an additional paper support overall to an original paper support.
- Lining means to adhere an additional fabric support (such as cotton, linen, or synthetic) overall to an original paper support.
- Mounting means to adhere an additional overall rigid support (such as thick-ply paper boards, honeycomb, or aluminum panels) overall to an original paper support.
The term mounting can also be used to denote different types of matting techniques and housing used for display and storage (not addressed in this section). General information on mounting, matting, and framing can be found in Exhibition and Matting and Framing.
When multiple types of supports are used, it is usually at the discretion of the author of the text as to what term is used. Please keep these nuances in mind as the terms will no doubt be used interchangeably within this text as practitioners with different training and language contribute.
Factors to Consider Before Backing, Lining, or Mounting
Historic photographs that were never mounted should remain unmounted whenever possible.
Attaching an additional support overall to a photographic material is considered when the original support materials have physically failed. Different backing, lining or mounting processes uses aqueous or non aqueous adhesives, natural or synthetic products, and many possible methodologies. Consider least invasive methods whenever possible.
Before doing these treatments, conservators must discuss preliminary considerations like the assessment of the photograph's value and significance versus damage; the theoretical considerations, and the treatment's risks depending on the photographic process.
Also, many variables influence treatment results. To perform a backing, lining or mounting without considering each of these factors or to restore with a deficient skill could create an irreversible damage to the aesthetic or material aspect, the value and the significance of the photograph.
These factors include the type of the adhesives used; the backing, lining or mounting support; the condition of the photograph before treatment; the humidity conditions of the conservation lab; damages of the photograph such as tears, folds and losses in the support of the photographs; the surface in which you brush the adhesive (in the the paper lining or the photograph reverse); the team work; and the drying process.
Purpose of adding an additional permanent support
- To re-establish the physical characteristics of the support of photography, depleted by tears, folds, cockling, curling, looses, friability; or to counteract distortions. This improves the handling and storage of the prints.
- To being barrier material between the support of photography and secondary support, which can be a new one or it can be the original historical support undergone treatment for de-acidification, washing or disinfection.
- To create a barrier material to reduce introducing texture from a secondary support or to facilitate a future unmounting treatment.
- To provide structural support when a photograph is not mounted, but when required.
Assessment of the photograph's value and significance versus damage
First, the conservator evaluates the characteristics of the photographs, from an aesthetic, historic, scientific and social point of view. Second, the conservator determines the condition of the print, interrelating how and to what extent the damages affect the value. Based on these factors, establish criteria for the appropriate level of treatment. If preventive treatments are insufficient to preserve a photograph's significance and value, then consider the more invasive treatment of adding a lining, backing or mount.
After recognizing the need for backing, lining or mounting of a photograph, any treatment proposal should establish these principles to support the treatment:
- To respect the photograph, preserving its tangible and intangible significance according to its historical technological, social and/or scientific value.
- Backing, lining and mounting treatments add new elements to photographic material. So, these treatments must not adversely affect the image, value, and meaning of the photograph, nor its eventual research and analysis. Minimum intervention required means that lining and backing should be the last treatment option considered.
- The backing, lining or mounting process and materials used must be reversible or re-treatable, allowing eventual treatments and analysis without affecting the physical integrity of the photography.
- Using compatible materials, not affecting the physical or chemical and dimensional stability of the photographs. Conservators must have knowledge about the material´s long-term behavior.
- "The conservation professional shall document examination, scientific investigation, and treatment by creating permanent records and reports"Code of Ethics AIC
Potential risks according to the photographic techniques
Choosing a support
Choosing an adhesive
Choosing a method
Choosing a method of flattening and drying
Helpful Equipment and Materials and Considerations for Use
The equipment chosen will ultimately depend on the needs of the photograph to be treated including process type, condition, size and the procedure chosen for treatment. Professional judgement is required as each photograph has a unique aging history. Not all the materials listed in this section will be needed for each project.
- Adhesives of choice: cellulose ethers, such as methyl cellulose (Methocel A4M®,Methylcelullose M5012®, Tylose® ) and hydroxypropyl cellulose (Klucel G®), refined wheat or rice starch paste (Aytex-P Starch®, Lineco®), commercial dry-mount and hand formulated heat-activated adhesives and tissues
- Drying, pressing, tensioning procedures: Drying rack, press, blotter stack, large sheets of plastic (thickness dependent on use), Japanese drying board (Karibari), Dutch strainer, etc.
- Photographic Grade Blotters: large sheets and small scraps. Do not use blotters with optical brighteners because the brightening agents can migrate to the photograph support during aqueous lining treatments.
- Large flat adhesive brushes: Often Japanese paste brushes (Noribake) or the joining/assembly brushes (Tsukemawashi or Kuroge-Tsukemawashi) are used. However, any brush that can impart an even, smooth distribution of adhesive will work, even commercial sign lettering brushes. Some conservators like thick brushes that hold much paste; others prefer thin brushes that hold less paste. Some conservators use short, others prefer long haired brushes. Longer width, larger brushes are often preferred for large scale projects for ease on the conservator. In addition, some conservators prefer darker brush hairs (e.g. horse hair) as shedding bristles are easier to see against light-colored mounting material. The opposite is also true: shedding light, white-haired bristles (e.g. goat hair) are easier to see against dark mounting material.
- Large flat smoothing brushes: Japanese smoothing brushes (Nazebake) are currently available with two different traditional fibers: Japanese hemp and Philippine hemp. Japanese hemp is generally softer and more pliable. The Philippine hemp is generally stiffer. Sometimes the two are combined in one brush to utilize the qualities of both fibers. Choose a brush that is best suited for the process at hand and the individual practitioner's style of working. If the photograph is a process that is sensitive or prone to scratching, consider using the softer Japanese hemp brush, brushing through many protective sheet layers, or using a soft paste brush as a smoothing brush instead.
- Squeegees, rollers: Both squeegees and rollers come in differing lengths and material hardness. Most are made of rubber or plastic. Commercial art, printmaking, and window washing/cleaning suppliers are good sources.
- Secondary mounting support (meant to stay with the photograph): Japanese papers, generally made of Kozo fiber either in sheet or roll form (examples include: Tengucho 116 10gr, Hozui Roll 24 gr, Kozo s 24gr, Tosa Tengujo, Sekishu Torinoko Gampi 20gr, Usuyo Gampi 9gr, Kizukishi 9 to 30 gr, thin Kozo 9gr, medium Kozo 25 gr), finely woven cotton or linen, paper-boards
- Poly (ester terethphalate) film: Commercial names MYLAR TYPE D, Melinex 516, Bollaré®.
- Poly (ester) fabric: Commercial names Dacron, Terylene, etc. Heavier weight, twill woven fabrics work better for larger Dacron-type linings
- Non-stick materials, the smoothest available: poly (ester) webbing (Holytex 3257), wax paper or other non-stick, texture-less sheet, Rayon paper, Silicone-release paper
- Tweezers: pointed tips and broad, flat without serrations
- Thin Knives, variety: thinned metal paintings spatula, thinned metal microscope tools, thinned metal micro-spatulas, thinned metal minarette tools, thinned Teflon knives, thinned bamboo knives
- Cotton, variety: rolls (also called "cotton wool" historically by British speakers), balls, swabs, pads of various sizes
- Fine mister: for water, perhaps water-alcohol mix. Some practitioners prefer hand-pump, some use aerosol or air-compression units. Some practitioners use only plastic containers, some use metal, such as the Japanese Dahlia brand. Some practitioners prefer using a traditional Japanese water brush (Mizubake) instead of a sprayer.
- Buckets, beakers, jars, or other: to hold water, dampen Dacron, etc.
- Trays or containers: with lids for adhesives and keeping brushes moist (if necessary)
- Towels and cloths: previously washed, clean, smooth, fine weave, natural fibers and microfiber cloths work best. Smooth, very absorbent paper towels are also used.
- Good overall light, with a separate movable, good raking light source
- Sanding equipment and personal protection equipment: to roughen any plastic boards if necessary for Dacron methods
- Vacuum-suction table: Gasket materials (MYLAR film, etc.)
- Hot press, iron, tacking-iron: for heat-activated adhesives
- Cooling Platen: smooth, glass or metal platen for dwell time cooling period when using heat-activated adhesives
Techniques for Backing, Lining, or Mounting Photographic Materials
Re-moistenable tissue method
Lining with aqueous adhesive (starch or starch with a cellulose ether) and drying under weight.
Dacron method (totally restrained on Dacron fabric on Formica, Plexiglas or glass support)
This process uses three pasting steps. Paste out a rigid support (a sanded Plexiglas or melamine support) and then lay down the Dacron. Again paste out the Dacron and lay down the backing support (Japanese or western paper pre-humidified). Paste out again and lay down the photograph, pre-humidified. Lay down a protection film like polyester web and brush/roll over the complete ensemble. Take out this last polyester web and the entire system is allowed to dry, with or without weight on top, exposed to the air, or under blotters or felts. Let it dry horizontally for at least 24 hours before the Plexiglas can be moved to a more vertical position to free-up table space. Let it dry for at least two days more: A week or so of drying is beneficial. Be careful during the first hours of the drying process, because tide lines, tears or cracks can be created from the tension. Once dried, release tension all the way around the Dacron and the paper or board mount (go in a few inches with a separating knife of choice), then take off the Dacron from the rigid support with a Teflon spatula or slide a dental floss between the rigid and Dacron surfaces. Place the photograph face down on a clean, dust-free surface and remove the Dacron fabric while holding the unit as flatly against the table as possible. Creases and older damage can occur to the photograph if care is not taken during this step. Sand off or reduce the excess adhesive as necessary or desired.
A modified Dacron technique (totally restrained on stretched Dacron support around a frame)
The Dacron fabric is stretched onto a frame, then placed onto a rigid support (a table or melamine top) and pasted out. The backing paper is laid down and pasted out. The photograph is laid down. The stretcher is lifted from the table. The ensemble can be air-dried in a vertical position. 
A) Peripheral & Formica glass
- Peripheral & Formica glass
B) Peripheral & Stretched Dacron
Photographs that were dry mounted historically, are candidates for remounting with dry mount method if they are physically able to withstand the procedure. Since the earliest efforts of mounting paper photographs (19thc.), using a thermoplastic, heat activated adhesive avoids the issues of aqueous adhesives on photographic material, such as paper expansion, warping and curling with drying, and potential water staining occurring. However, some conservators prefer to attach a Japanese paper, often with wheat starch paste, before dry mounting as an interleaving paper to help assist future reversibility. The tips given here are from Gary Albright (2017). See Unmounting for additional information regarding dry mount materials and resources.
Know Your Dry Mount Press
Before attempting any dry mounting of historic materials, it helps tremendously to be familiar with the press or heat process to be used.
- Size. Know the dimensional restrictions of your commercial press. If multiple heating situations are required for mounting, they should be orchestrated carefully before any mounting effort is made. Consult your press instruction for mounting large items.
- Pressure. The pressure exerted by a commercial dry mounting press or hand-held irons will vary. Press pressure can be altered either mechanically or by varying the thickness or hardness of the dry mount press sponge pad. Thinner pads can be adjusted to the proper height with the addition of rigid paper boards placed beneath them. See your presses instruction for adjusting the pressure bar for the platen, also, to ensure even pressure overall.
- Temperature. Knowing the temperature range (minimum to maximum) and the range across the platen is also essential. Working between 150-250°F (65-93°C) is often preferred for photographic materials. Always be cautious and err on using lower temperatures, especially for plasticized photographic materials such as resin coated (RC) papers. Best results are achieved with dry heat: Combinations of moisture and heat can be problematic for photographic materials.
- Cleanliness. Ensure that your sponge pad is in good condition. If not, replace before mounting. Ensure that the press platen is clean of any dust, paper, remnants, or old adhesives as these will leave impressions in your photograph.
The Dry Mounting Process
Pasche's (2008) book on dry mounting offers much sound advice. Likewise, existing online are many excellent framing and photographer's dry mount videos. If new to the process of mounting, reading about and watching several different skilled practitioners can be instructive to understand the attention to detail and nuances that create the difference between a good and poor dry mount. A poor mounting process can endanger the historic item and require it be subjected to additional heat, mechanical, or chemical means to release. Different types of dry mount papers are commercially available. Many dry mount adhesives also claim solvent release, however, release is usually easiest nearer the time of mounting.
- Pre-drying any folders and support materials will improve the mounting process. Preparing all materials before hand and organizing them logically on a work table is essential to doing a good job. Materials might include the dry mount adhesive tissue cut to slightly less than, yet almost the same size as the photograph, the mount chosen, and any smooth, new folders and silicone release papers.
- Tack the dry mount tissue onto the back of the photograph to ensure it doesn't slip. Tack once, near the center. Multiple spots can impede expansion or create rippling issues with the adhesive. Likewise, tack the photo-adhesive unit to the mount before placing in the press to ensure alignment doesn't shift.
- Heating: First ensure the press is at the desired temperature. Release paper can create a folder or is placed either on top of the photograph. Heat with the photograph face-up, often for 30 seconds (press-temperature and type of dry mount chosen may vary the time), and turn over the folder or packet and heat the back for 15 seconds (or so, again this is approximate) to even out the heat distribution.
- Cooling: After heating, immediately place the packet under light pressure between two very smooth, regularly even materials such as a table-top and a flat, cool platen, such as metal flattening plates specifically designed for this use, glass, Plexiglas (acrylic), or smooth melamine table tops (without legs).
Effects of Backing, Lining, and Mounting Photographic Materials
While very interventive, providing a new secondary support can extend the use and appreciation of historic photographic materials. Images can be reintegrated when separated. Materials can be handled more safely in study collections (appropriately sleeved, of course). Matting, framing, and exhibition of photographic materials may be made easier.
Many photographs were traditionally mounted to mimic a contemporary cultural practice such as a carte' de visite or cabinet card, or to prohibit curling (albumen) or to protect them from physical abuse. Photographs created in the earlier era of photograph history can be on extremely thin papers. Photographs can need to be backed, lined, or mounted because of damage or size in handling.
Color of the mounting, reinforcing material affects the visual look of the photograph. Consider the traditional colors of the mounting support (gray, brown, or dark colors) when choosing modern mount materials. Thin photographs may benefit from lighter toned backing materials. If the photograph will be matted, colored mats can be combined with neutral colored mounting materials.
Extremely large photographs can be mounted historically to cloth for support during display, ease of handling and storage. When remounting these on cloth, choosing a tight weave, consider material without much expansion nor contraction issues, and consider multiple interlayers of paper to soften any weave patterns.
Resources and Further Reading
- Albright, Gary. 2017. Using the Dry Mount Press in Conservation Treatments, Presentation Handout, AIC-PMG Winter Meeting, Kansas City, MO.
- Brueckle, Irene. 1997. "Update: Remoistenable Lining with Methyl Cellulose Adhesive Preparation." Topics in Photographic Preservation, vol. 7, p. 88-90. Washington, D.C.: American Institute for Conservation.
- Cannon, Alice. 2011. "A Review of lining methods for paper-based Photographic Prints from the Nineteenth and Twentieth Centuries." Studies in Conservation, vol.56, number 3, p. 167-178. London:International Institute for Conservation of Historic and Artistic Works (IIC).
- "Doublage" method. 2000. Mellon Workshop in Photograph Conservation: Unmounting and Mounting of Photographic Print Materials, March 13-17, 2000.
- Guzmán, Estíbaliz. Consideraciones previas y factores involucrados en el laminado de fotografias blanco y negro en soporte de papel de fibra. Proyecto final. ENCRyM, 2009.
- Hamburg, Doris and Tim Vitale, compilers. 1988. Chapter 28, "Drying and Flattening." Paper Conservation Catalog (Outline). AIC-Book and Paper Group. Washington, D.C.: American Institute for Conservation http://www.conservation-wiki.com/index.php?title=BP_Chapter_28_-_Drying_and_Flattening
- Herrera, Rosina. 2005. Alfred Stieglitz's Mounting Method for Gelatin Silver Prints - Three Case Studies at George Eastman House Collection. Advanced Residency Program in Photograph Conservation paper. Available at: http://notesonphotographs.org/images/3/36/Stieglitz_mounting_final_for_web.pdf (accessed September 2015)
- Kellogg, David. 1988. The Permanence of Dry Mounting Tissue and its Effects on Black and White Photographic Prints Under Controlled Humidity and Accelerated Aging Conditions. Unpublished research, courtesy of Jose Orraca & Barbara Lemmen.
- Kennedy, Nora. 1988. "Three French Photographic Conservation Techniques." Topics in Photographic Preservation, vol. 2, p. 40-49. Washington, D.C.: American Institute for Conservation.
- "Le Fond Tendu: A French Lining Technique." 2000. Mellon Workshop in Photograph Conservation, Unmounting and Mounting of Photographic Print Materials, March 13-17, 2000.
- Maver, Ian. 1992. “Some Research into Methods of Mounting, Lining or Repairing Albumen Prints.” The Imperfect Image: Photographs their Past, Present and Future, p. 311-315. London, UK: The Center for Photographic Conservation.
- McCabe, Constance and Mary Lynn Ritzenthaler. 1988. "The Use of the Suction Table for the Conservation of Photographic Prints." Topics in Photographic Conservation, vol. 2, p. 50-55. Washington, D.C.: American Institute for Conservation.
- Nicholson, Kitty and Susan Page. 1988. "Machine Made Oriental Paper in Western Paper Conservation," The Book and Paper Group Annual, vol 7. p. 44, Washington, D.C. American Institute for Conservation: http://cool.conservation-us.org/coolaic/sg/bpg/annual/v07/bp07-08.html
- Nieverland, Ingelise. 1995. "Lining and Backing: the Support of Paintings, Paper and Textiles." United Kingdom Institute for Conservation (UKIC) [currently ICON]
- Norris, Debra Hess. 1996. "Current Research Needs in the Conservation Treatment of Deteriorated Photographic Print Materials". Research Techniques in Photographic Conservation: Proceedings of the Conference in Copenhagen, 1995. p. 1010-105. Copenhagen, Denmark: Royal Danish Academy of Fine Arts, School of Conservation
- Page, Susan. 1997. "Conservation of Nineteenth Century Tracing Paper: A Quick Practical Approach." The Book and Paper Group Annual, vol. 16, p. 67-73. Washington, D.C.: American Institute for Conservation. 
- Paschke, Chris. A. 2008. 3rd edition. The Mounting and Laminating Handbook. CA: Designs Ink Publishing.
- "Press Mounting Technique." 1993, September. Unmounting Photographs Workshop, Jose Orraca Studio, Kent, CT, USA
- Owen, Antoinette, compiler. 1994. Chapter 29, "Lining." Paper Conservation Catalog, AIC-Book and Paper Group, Washington, D.C.: American Institute for Conservation, Book and Paper Group 
- Digital versions of AIC-PMG's TOPICS OF PHOTOGRAPHIC CONSERVATION articles are available on Conservation OnLine
- Wagner, Sarah. 1991. "Conservation Tip: A Modified Dacron Lining Technique for Photographs." Topics in Photographic Conservation, vol. 4, p. 31-33. Washington, D.C.: American Institute for Conservation.
- Wagner, Sarah. 1997. "Remoistenable Tissue, Part II. Variations on a Theme." Topics in Photographic Conservation, vol. 7, p. 91. Washington, D.C.: American Institute for Conservation.
- Wagner, Sarah S. 1991. "Conservation Tip: A Modified Dacron Lining Technique for Photographs." Topics in Photographic Preservation vol. 4, p. 31-33. Robin E. Siegel, ed. American Institute for Conservation, Washington D.C.
- Wagner, Sarah and Barbara Lemmen. 2000. "Double-sided Remoistenable/Solvent or Heat Activated Tissue." Mellon Workshop in Photograph Conservation: Unmounting and Mounting of Photographic Print Materials, March 13-17, 2000.
- Wagner, Sarah and Barbara Lemmen. 2000. "The Use of Solvent- and Heat-Activated, Pressure-sensitive and Re-moistenable Systems in the Mounting of Photographs." Mellon Workshop in Photograph Conservation: Unmounting and Mounting of Photographic Print Materials, March 13-17, 2000.
- Wagner, Sarah and Barbara Lemmen. “The Use of Solvent- and Heat-Activated, Pressure-sensitive, and Remoistenable Systems in the Mounting of Photographic Materials.” Typed notes from the Mellon Workshop in Photograph Conservation: Unmounting and Mounting of Photographic Print Materials, unpublished, bound, residing at the George Eastman House, March 13-17, 2000, 8 pp.
- Wagner, Sarah and Barbara Lemmen. 2000. "Klucel G Tissue and Remoistenable Tissues (MC/WSP or MC)." Mellon Workshop in Photograph Conservation: Unmounting and Mounting of Photographic Print Materials, March 13-17, 2000.
- Wilhelm, Henry G. 1993. "Print Mounting Adhesives and Techniques". The Permanence and Care of Color Photographs. Grinnell: Preservation Publishing Co. 367-383.
- Wagner, Sarah S. 1991. "Conservation Tip: A Modified Dacron Lining Technique for Photographs." Topics in Photographic Preservation vol. 4, p. 31-33. Robin E. Siegel, ed. American Institute for Conservation, Washington D.C