"Conservation framing must employ materials and techniques which will produce only a minimum of change in the artwork, helping to keep it as close to its original condition as possible."

Hugh Phibbs
Using archival quality matboard with nonarchival adhesives and tapes defeats the purpose of protecting an artwork. Most household or hobby glues and general purpose tapes are not suitable for archival mounting or matting. These tapes and adhesives commonly contain substances that are harmful to artwork on paper.

Adhesives used with paper may be divided into two groups by their method of activation: water or pressure sensitive.

1. Water activated adhesives become sticky when wet. They are usually made from animal, vegetable and mineral sources. The best for paper is vegetable based, especially wheat and rice starch pastes. Emulsions from synthetic polymers are not reversible* and are too strong to be used directly on the artwork. Synthetics have not been time tested.

Wheat and rice starch pastes are customarily used for museum mounting with hinges.** These pastes require some skill in preparation;^ proper measuring, mixing and cooking are important. They have a short shelf life. Well-cooked they last a few days if sealed at room temperature. Refrigeration causes the water to separate from the paste; this is called retrogration. Retrograde paste isn't effective. Pre-cooked starch paste and "ready-to-use" hinges typically contain a fungicide. Fungicides are known to turn adhesives yellow, which in time will turn the artwork yellow. Pre-gelled pastes which have been fully cooked and then dried are available. These come as a powder to which cold water is added as the paste is needed. Since it is stored in dry form, a fungicide is not needed. Once the water is added watch for mold.

Methyl cellulose paste^^ is used for conservation mounting with hinges. It requires no cooking (just mix with cold water), is non-acidic, resists mold, is reversible and has an indefinite shelf life. Methyl cellulose does not have the adhesive quality of starch paste, so when mounting large works, use more hinges across the top. Since it is a synthetic bond, it has not yet been time tested.

Gummed linen tape is coated with an acid-free water-activated dry adhesive. It will not stain and is reversible with water. It is used for hinging the window mat to the mounting board. Linen tape is not recommended for mounting artwork because of its strength*^ (except for artwork on thick paper, i.e., 300+ pound watercolor paper). Gummed paper tape, either white or brown packing tape, called butcher tape, has a reversible adhesive but it is not long lasting. The paper is acidic. Never use this tape for mounting artwork.

2. Pressure-sensitive adhesives and tapes should not be used for hinging valuable art because they are not reversible, and they may migrate into the artwork itself. These adhesives use rubber or acrylic compounds that may or may not be modified with plasticizers and tackifiers. Rubber oxidizes, hardens and gives up its hold. As modified acrylic adhesives**^ age, they may move in and around the paper fibers making it difficult to remove. Solvents may leave tide lines which will appear later. Heat activated acrylic will migrate rapidly and move into the paper fibers. Re-heating pushes the adhesive further into the paper. Cellophane and masking tapes will yellow in a short time, are corrosive, leave a residue, and are not reversible. Pressure sensitive tapes (plastic, transparent, cellophane) and adhesives should not come in contact with valuable artwork.

Pressure-sensitive linen tape is designed to hinge the window mat to the mounting board. It is acid-free but the adhesive is not reversible. It should not be used to mount artwork.

Alternatives to hinges and pastes are mounting corners and strips. These methods require no attachment to the art and are easy to use. Mounting corners are made of paper or Mylar and adhere to the mounting board. The artwork is slipped into the four corners. This is an effective alternative to hinges if the artwork is small enough not to break the corners and rigid enough not to slip out of them. Also the artwork must be overmatted so the corners don't show. Mounting strips are made of 100% rag and hold the artwork in place from the sides, top and bottom instead of the corners. For preservation protection, use only archival quality corners and strips. When using either mounting strips or corners, be sure to allow the artwork breathing space to expand. This will be discussed further in a future article on mounting artwork. Instructions on how to make mounting corners and strips are in Introduction to Matting.

For more information using hinges, mounting corners and strips see Introduction to Matting. Ask your local art store to show you their selection of matting supplies, mounting corners and strips, adhesives and tapes.

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*Reversible means, by moistening the adhesive with water, the artwork may be removed from the mounting board without pulling paper fibers from the artwork or leaving glue traces on the artwork.

**Hinges made of rice paper are adhered to the back of the artwork and to the mount board with a paste.

^For more detailed information see "The Hinging of Works of Art on Paper" by Hugh Phibbs, Picture Framing Magazine, February 1994; "Preservation/Conservation Framing" by Jared Bark, Picture Framing Magazine February 1993; The Framer's Book by Paul Frederick, CPF.

^^For further information see The Framer's Book by Paul Frederick, CPF; Curatorial Care of Works of Art on Paper by Anne Clapp.

*^Hinge papers should be weaker than the paper support that is to be hinged. Under stress, the hinge should tear before the artwork is torn.

**^See Phibbs, Picture Framing Magazine, 1994.