by Terry Whittier 11/14/94
Permission is granted to reproduce this article for free distribution. I can send you camera-ready copies. Copyright 1994 by Terry Whittier, 7059 Via Blanca, San Jose, CA 95139 (type font: GillSans 10 pt. in MacWrite) Assistance from Gerald Perkins.
Here's Light Impressions new PO Box address effective June 1st, 2000:
Light Impressions
PO Box 22708
Rochester, NY 14692-2708
1-800-828-6216
The main enemy from within is the remaining acidity or alkalinity from the manufacture of the paper or board. Nasty chemicals are usually used to produce paper products from wood and some plants. Some acidic or alkaline chemicals can remain in the paper, causing it to chemically change with age and turn yellow or brown. A paper that is pH neutral is balanced between acidity and alkalinity (the pH balance) and therefore will tend not to discolor with age due to interaction with any chemicals contained within the paper itself. Some papers are buffered, meaning that they have chemicals added during production that tend to offset the harmful chemicals.
Some papers are 100% rag. These tend to be free of harmful chemicals. Rag paper is made from fibers other than wood cellulose. These can be made from cotton, wool, synthetic fibers, etc. These fibers are aligned in one or more directions (grain) and glued with any of a variety of substances (sizings). Not all pure rag papers are completely archival (capable of long life without chemical change or discoloration) but most are.
Some common copier papers are fairly pH neutral. Some are very acidic. Use a pH testing pen to check them, if you need to.
When buying paper or board, be sure of what you are getting, if you want archiveability. Or test for pH with a testing device, such as the pH testing pen offered through Light Impressions supply company for only $6 or less. It's a good investment...amaze your friends as the dye turns yellow to indicate highly acidic paper!
Outside nasties are self-adhesive tape, glue, humidity, skin oils, temperature, aerosols and ultraviolet light.
The sticky coatings on adhesive tape contain volatile chemicals that can work their way into the paper and stain it. Plus, the adhesive will eventually dry with age and come loose. The plastic that forms the body of adhesive tape may also contain solvents that can migrate out and contaminate the artwork The worst of the commonly used tapes are masking tape and cellophane tape, although duct tape, drafting tape or any self- stick tapes are bad.
The best tape to use is pH neutral cloth or paper tape that has a water-soluable adhesive. This kind of adhesive will not ooze into the paper of the artwork and can be removed cleanly with a moist cloth.
The best way to secure an original work on a board is with archival corners. That way, no adhesive touches the art, thus eliminating one major route of contamination. Using corners made of acid-free paper and secured with water-soluable adhesive or tape is the best possible mounting technique. (For added safety, place a sheet of pH neutral paper between the artwork and the mounting board.) (Matte board is usually pH neutral on the white back but acidic on the color front and between the faces.) Use spray adhesive only on a copy or print that you can replace if it deteriorates.
If you write to me, I can send you a free sample of the archival tape that is available. It can also be simply folded for use as archival corners.
If tape is used directly on the front or back of the original, it is best to use water-soluble glue tape and as little of it as possible. Keep in mind that you may want to re-mount the art at some future date and it might be decided at that time to trim the original to remove adhesive. Leave as much room as possible around the image for this.
Mylar is the second best option because of its chemical stability. Polypropylene, Plexiglas, or any of the hard plastic sheets are almost as good as mylar and will do nicely for a few years before requiring replacement. Vinyl is the worst choice, since it's the softest and therefore contains the most potential for contamination.
The softer and more flexible the plastic, for any given thickness, the more solvents and emulsifiers that it contains. These chemicals evaporate out of the plastic and sometimes accumulate on the surface of the plastic. Most of these substances will cause damage or discoloration to artwork as they accumulate on or chemically combine with the artwork.
To prevent UV light from accelerating the aging of art, avoid direct or very bright reflected sunlight. It might be wise to avoid very bright fluorescent lights, particularly daylight types.
Naturally, any contaminants such as smoke or aerosol chemicals that could condense on or infiltrate the art must be avoided.