PMG Section 1.5.6 Framing Materials
Photographic Materials Conservation Catalog
Exhibition Guidelines for Photographic Materials
Date: July 2004
Contributors to WIKI version: Your name could be here!
Compiler: Stephanie Watkins, 1993-2004
Initiator: Douglas Severson, 1992-1993
Contributors (Alphabetical): Catherine Ackerman, Nancy Ash, Sarah Bertalan, Jean-Louis Bigourdan, Barbara N. Brown, Ed Buffaloe, Carol Crawford, Corinne Dune, Thomas M. Edmondson, Debra Evans, Julia Fenn, Betty Fiske, Gwenola Furic, Judy Greenfield, Doris Hamburg, Marc Harnly, Pamela Hatchfield, Cathy Henderson, Nancy Heugh, Ana Hofmann, Emily Klayman Jacobson, Martin Jürgens, Nora Kennedy, Daria Keynan, Lyn Koehnline, Barbara Lemmen, Holly Maxson, Constance McCabe, John McElhone, Cecile Mear, Jennifer Jae Mentzer, Jesse Munn, Rachel Mustalish, Douglas Nishimura, Leslie Paisley, Sylvie Pénichon, Hugh Phibbs, Dr. Boris Pretzel, Dr. Chandra Reedy, Nancy Reinhold, Andrew Robb, Grant Romer, Kimberly Schenck, Douglas Severson, Tracey Shields, Angela Thompson, Sarah Wagner, Clara von Waldthausen, Dr. Mike Ware, Stephanie Watkins, Dr. Paul Whitmore, Faith Zieske, Edward Zinn.
First edition copyright: 2004. The Photographic Materials Conservation Catalog is a publication of the Photographic Materials Group of the American Institute for Conservation of Historic and Artistic Works. The Photographic Materials Conservation Catalog is published as a convenience for the members of the Photographic Materials Group. Publication does not endorse nor recommend any treatments, methods, or techniques described herein.
Preferred framing materials
Anodized aluminum frames are recommended instead of wood. As Wilhelm (1993, 511) explains, they "are inert, inexpensive, lightweight, and unaffected by moisture fluctuations. Stainless steel and brass are also safe, but are expensive and heavy." The Polaroid Corporation (1983, 33) agrees citing aluminum, stainless steel, materials coated with baked enamel, and epoxy powder-coated welded aluminum frames as inert construction materials.
Wood and wood composites
- Ideally, wood and wood composites should be avoided when framing photographic materials. Wood and wood composites can release acetic acid, formic acid, propionic acid, isobutyric acid, alcohols, and formaldehydes in varying amounts. According to Cecily Grzywacz, scientist at the Getty Conservation Institute (1999), "The specific acidity of a wood board is dependent on the felled tree. In other words, there is variance within species." In addition, some woods may have been processed or treated with insecticides that have undesirable effects (Craddock 1992, 24). Particleboard and plywood are manufactured with urea-formaldehyde, melamine-formaldehyde, and phenol formaldehyde adhesives that can off-gas "phenol from resin, hydrochloric and other acids from hardeners, ammonia, hexamine or melamine from the retarders" (Raphael 1991, 7). The Polaroid Corporation (1983, 33) recommends that for Polaroid® material, "plastic and wooden frames should be avoided."
- Economic costs and aesthetic concerns may occasionally outweigh the risks of potentially damaging side effects from wooden frames. Wilhelm (1993, 511, 534) conceding that wood will be used despite the risks, mentions well-dried maple, birch, or basswood as preferred for use with photographic material. When contemplating the use of wood near photographic materials, the following characteristics should be considered (Anderson 1991; Raphael 1991; Craddock 1992; Greenfield n.d. [ca. 1992]):
- Least acidic woods: Aspen, American (Swietenia group) or African (Khaya group) mahogany, balsa, basswood, birch (not yellow), eastern hemlock, sweet gum, yellow poplar, walnut, Sitka spruce, and tropical iroko, ramin, and obeche woods. True mahogany is considered the best wood choice, however, it is expensive and difficult to obtain. Several types of native mahogany species are on endangered species lists, like the Convention on International Trade in Endangered Species (CITES). Introduced mahogany species may be exempt from the endangered species restrictions. Current availability and source origin should be checked before use.
- High acidity or corrosive woods: DO NOT USE! Ash, steamed beech, yellow birch, butternut, red and western red cedar, sweet chestnut, cypress, elm, Douglas fir, hickory, larch, oak (new or well seasoned), particleboard, pecan, pine (white, southern yellow, loblolly), plywood, redwood, spruce (not Sitka spruce), and teak.
- Yellow pine is close to neutral pH, but gives off other organic gases that are harmful to materials other than metals (Craddock 1992).
- Newly made wooden frames should be coated at least one month to six weeks prior to framing to seal pores, create a more uniform film coating, and off-gas volatile diluents. The coating chosen must not contain or release pyroxylin (cellulose nitrate), formaldehyde, phenols, acids, ammonia, hexamine, melamine, or peroxides (Raphael 1991). Paints seen as suitable, such as acrylic paints, can obscure the wood, negate the aesthetic look desired, and may be only partially effective in preventing acidic off-gassing from the wood. Latex paint is not a vapor barrier and may also contain bacteriocides (Greenfield n.d. [ca. 1992]).
- Wooden frame rabbets and interiors may be blocked with foil-backed adhesive tapes, aluminum, nylon or poly (ethylene) films and barriers (such as Rosco Cinefoil™ and Marvel Seal 360®) to reduce potential off-gassing during short-term displays. In addition, sealing the glazing and mat as a unit with a foil-backed adhesive tape before framing can help reduce off-gassing from wooden frames and outside sources from reaching the photographic material. Materials with zeolite molecular traps or activated carbon may absorb potentially damaging gasses from wooden frames and environmental sources. Carbon can re-emit absorbed contaminants during long-term storage, but this is not likely to occur over the course of an exhibit.