Conservation Framing
Conservation framing is highly recommended when a client seeks to frame artwork that has either monetary, historical or personal value. Aside from the aesthetic considerations when choosing mats and moldings, it is important to choose materials that are considered archival. The following are thumbnail descriptions of conservation materials used in framing.

Matboard - Only lignin-free (acid-free) matboards can be considered truly safe for fine art. Rag mat is still considered the industry standard, although the alpha cellulose boards are also excellent. Never use standard wood pulp board on a valuable piece. The mat should be hinged to the backing board with a water-activated linen tape, so that the package opens like a book. Of course, the backing board should also be conservation quality.

Glass - Conservation glass should be used to filter out light in the harmful 200-400 wavelength range. This will protect the artwork from bleaching, color fading, yellowing, etc. Conservation quality glass is also available colorless and in non-glare.

Hinging of Artwork - The best hinging material for valuable or fragile works on paper is Japanese tissue adhered to the backboard by a cooked rice starch paste. This combination has been used for many years and is completely acid-free. It also remains reversible indefinitely, a quality not found in most commercial acid-free hinging tapes. Hinges can be applied in several different configurations, such as "T" hinges, "V" hinges, etc. The key to hinging valuable artwork is to make certain the hinging paper is weaker than the paper; this insures that if the framed piece is jolted or falls, the hinges will tear but not the artwork.

Example: How Would a Museum Handle, Say, a Rembrandt Etching/
The first consideration would be the matboard and backing. 100% rag board would most likely be used for both. If the framer is leery of the print touching the glazing material, a double mat or deep bevel (8 ply) mat would be used to provide added space. The print would be hinged to the rag backboard with cooked starch paste and torn Japanese tissue. The mat would then be hinged to the backboard with linen tape, creating a “book” in which the print is protected.

The glazing material would be UV filtering glass or plexiglas. Some museums are partial to plexi, since it will not shatter if the piece is dropped. Next, the frame must be treated to insure that acid migration cannot occur. This is done by shellacking the rabbet of the frame and then lining it with either 2 ply rag barrier paper or acid-free tape.

The matting and glass can be secured in the frame with either diamond points, glazier’s points or wire brads. The entire package is then sealed on the back with acid-free barrier paper. Some museums use barrier paper that prevents all moisture from penetrating the frame package; others use paper that is somewhat porous.

The finished piece can either be hung on wire strung across the back on metal “D” rings or it can be hung on security hangers. Security hangers insure that the artwork cannot be removed from the wall without the type of wrench made specifically for security hangers.

Special Considerations When Handling Paintings – The vast majority of paintings are done with either oil or acrylic paint, although occasionally you may come across one done in egg tempera or encaustic. (Water colors on paper will not be addressed here, since they are typically handled the same as prints.) Glazing is not required for paintings on board or stretched canvas, yet it is highly recommended that the painted surface be prevented from touching the wood rabbet of the frame. There are two reasons for this: 1) There is acid in the wood of the frame; 2) Over time, a painting can stick to the frame’s rabbet. Once this happens, it is very difficult to remove the painting without damaging the paint. Museums have traditionally created a barrier by shellacking the rabbet and lining it with felt, but 2 ply rag mat can also be applied to prevent damage to the art.

Paintings on stretched canvas are also vulnerable to physical assault from the back. Several types of barriers can be applied to the back of the frame to prevent damage; plexiglas is a good option, since it is light and durable. Paintings on wood panels are susceptible to splitting, so they should never be hung above a heat source or in an area of dramatic temperature or humidity variations.

All paintings eventually get dirty and can benefit from cleanings every couple of years. After being cleaned a painting should be coated with a clear sealant (typically varnish) to protect it and to make it easier to clean in the future.