Methods
Preservation mounting is the ultimate; the only method endorsed by all preservation authorities. Usually, the art paper is hinged at two or more points along its top edge by special Japanese paper and starch paste, to 100% rag board backing. Other preservation-grade mounts may be devised as needed, but must meet these criteria:
- No permanent changes to the artwork; mount must be completely reversible with non-destructive methods and materials.
- All materials in contact with the artwork must be 100% rag or alpha-cellulose board. Minimum acceptable barrier is 4-ply (standard matboard thickness).
Hinge mounting uses linen, paper , or special tape to fasten top edge (only) of artwork to backing; usually reversible & causes little damage to artwork, but adhesives and materials are not preservation-grade.
Wet mounting uses water-base adhesive (similar to wallpaper paste) to glue paper down to a backing board. Considered permanent, but might be reversed by soaking artwork in water. Best done with a vacuum press.
Dry mounting uses heat activated adhesive tissue and a heated press, with or without vacuum. Considered permanent; sometimes reversible with heat or solvents.
Spray mounting uses solvent-base aerosol adhesive. Considered permanent; sometimes reversible with solvents. Best done with a vacuum press.
Sink mount is a "nest " beneath the mat, for art that is thicker than normal. Usually, adhesives are not in contact with artwork; this may be an acceptable preservation-grade mount if 100% ragboards are used to make the sink.
Photo corners may be purchased or custom-made to fit. Good for photos and other rigid-paper art. Gravity works against these mounts; art paper may sag and wrinkle horizontally.
Mounting Boards
Matboard is often used as a backing board for mounting. It may be standard wood pulp, alpha-cellulose or 100% rag, depending on quality requirements of the project. For large pieces, added backings may be needed for stiffness.
Foam-center board is Styrofoam with paper covering on both sides; smooth white surface; limited acidity. Also available with acid-free or 100% rag paper covers, but never preservation-grade because of out-gassing problems.
3X board is heavy cardboard (similar to illustration board) with smooth white surface; acidic wood pulp paper.
Recommendations
Preservation mounting should be used for all original art, collectible prints, and items of sentimental value.
Wet mounting under vacuum is recommended for porous paper which has no significant value, such as posters & maps. Most stable over time. NOTE: backing board may warp, if not framed.
Dry mounting is recommended for photos and other non-porous paper artworks which have no significant value. Over time, drymount tissue may deteriorate and loosen the mount in spots.
Other mounting methods and materials should be chosen when most appropriate for the art, equipment and materials available.
Avoid the use of mounting materials unsuited for the purpose:
- Masking tape - acidic; adhesive made for temporary uses.
- Rubber cement - acidic; causes discoloration; deteriorates rapidly.
- Very acidic materials like corrugated cardboard, Masonite, plywood.
Glass
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Clear picture framing glass is most common and least expensive for general purposes. Often called "regular" glass, but should not be confused with lower-quality window glass.
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Non-glare glass is about twice the price of clear glass. Its etched surface blurs the image when viewed from side angles, especially when glass is properly separated from the art surface; more separation, more blur.
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Ultraviolet-filtering glass is available clear or non-glare, and is recommended for all preservation projects. It is coated inside to filter out more than 95% of harmful UV light, which causes fading. UV rays are in all light, but very strong in sunlight and fluorescent light. Cost of UV-filtering glass is about the same as non-glare glass.
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Reduced-reflection glass is available with or without UV-filters. It is not etched like non-glare glass, but is coated on one or both sides. The metallic coatings disperse reflected light and allow better clarity that any other glazing. In some conditions, it looks like there is no glass at all. This is relatively new to the framing industry, and is not yet available with UV filters. Cost is 4 to 10 times that of regular glass.
Plastic
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Acrylic looks similar to glass, but costs more, and requires more labor for the framer. It is light weight & shatter-resistant. Disadvantages: scratches easily; makes static electricity (deadly for fugitive media); it is more flexible than glass and tends to distort in large sizes. Available in several thicknesses, with or without UV filters.
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Styrene is a cheap substitute for acrylic, with similar characteristics. It looks the same when new, but becomes yellow and brittle with age.
Flexible laminates
may be used on posters, photos, other easily-replaced, disposable or temporary art. Laminates are thin vinyl with adhesive on the back, and come in several textured, matte or glossy surfaces. Some kinds have pressure-sensitive adhesive, which can be applied with a brayer. Others have a heat-activated adhesive, designed for application in a drymount press. Laminating is permanent and should not be considered for any preservation project.
is the first step of picture framing, when choices are made about how best to present and preserve the art. Done well, framing design is a thoughtful process and your art deserves the effort.
