We hear a lot about "acid-free" or "archival" materials when handling, storing, or presenting artwork, and most of us understand what this means on a general level though not necessarily all that it involves or what specifically it means. When looking through old photos before my reunion last fall, I noticed that many of the pictures had faded and, in some cases, started to disappear altogether. At the time they were taken, in the 1980s before I ever started to hear about "buffered" papers or the dangers of magnetic photo albums, I dutifully filed each and every photo away in magnetic photo albums (I have nine) believing that this was the best way to protect them.
These days, I don't get prints made unless they're being framed or put into a portfolio, so at least they're safe from those albums. Except that just a few days ago while searching for a print, I noticed that in one of the storage containers several of my printed photographs had yellowed in a funny pattern that was suspiciously in the shape of the piece of cardboard behind them. I'm in really over my head, I thought.
Rather than just assume that I knew what I was doing and that the way I was storing prints and even negatives was safe, I did what I should've done a long time ago - I actually researched it.
For a material or method to be archival, the materials used in the process or that come into contact with the artwork must be chemically-stable with a neutral or slightly basic pH, durable, permanent, and protect the artwork from deterioration from environmental factors. Humidity, temperature, exposure to ultra-violet light, and pollutants from chemical off-gassing will all contribute to the degradation of photographs at varying degrees. Avoid attics and basements, which seem like the a great location for storage but are more likely to have temperature and humidity fluctuations, as well as in laundry rooms or directly near a bathroom, as both can create steamy conditions and elevated temperatures. An internal closet away from these areas would work great.
Common labels found on archival materials include "acid-free" and "lignin-free". Honestly, I'm a little embarrassed that I never took the time to learn more about this or even consider the importance of these aspects, particularly when handling my own photographs, and even more so because I have a science background. So, I asked my friend Jennifer Wade, who previously worked with conservators at the Library of Congress to identify materials present within artifacts to determine safe-handling methods, to help explain:
Paper can "yellow" in three ways:
1) Lignin, a component of plant cell walls, turns yellow when exposed to heat or UV light. Papers that have a lot of lignin will yellow more.
2) "Acid-free" means that a buffer has been added to the paper during the manufacturing process that keeps the pH nice and stable at about 8.5. Un-buffered paper is around pH 7. Acids present within the paper will cause the paper to become fragile and brittle and lead to yellowing. Acids may also be leached from materials that come into contact with it, like cardboard and foam-core board.
3) Oxidation of trace iron and magnesium in the paper cause browning.
All of these can happen together, which is why buffers are added and materials are protected from light, which takes care of most of these problems. If you aren't sure if a material meets these requirements, use a pH pen to test it.
And, in general, the term "yellowing" basically just means a paper losing its brightness. There's even an actual "yellowness index" which is a spectral term for the reflectance of the paper. You know when you buy a ream of paper, and it has some brightness number? That's how white the paper is, and the blue end of the spectrum is considered 'bright.' In fact, before fancy papermaking, they used to add actual bits of ground up blue minerals into darker paper to make it appear brighter! - who knew??
Film negatives, which are obviously not made of paper, must also be handled in a way to preserve their integrity. Storage sleeves should be made of polyester, polypropylene, or polyethylene.
When looking for storage containers for prints and negatives, I never understood why they were never sealable or air-tight, which I figured would protect from moisture, bugs, and dirt. Well, it turns out that airflow is your friend (as long as it's around the proper humidity) as it doesn't trap any chemical off-gassing or hold in any moisture that may already be present in the works.
Ideal Storage Conditions:
Cool and dark at around 68°F (20°C) with 30-40% relative humidity
Labels to look for:
Archival
Acid-Free
Lignin-Free
Buffered
Avoid:
Adhesives and tapes
Cardboard
Glassine
Kraft paper
Newspaper (treat with deacidification spray prior to storage)
Paper Clips
Plasticizers or materials containing them
PVC
Rubber Bands
Sharpies & other non-archival markers
Wood
For more information on archival storage of photographs and negatives, the Library of Congress offers preservation tips as well as a white paper on film storage. The National Archives addresses what you should do about those magnetic photo albums.
How do you store your artwork? Do you have any favorite brands or methods? Let us know in the comments!
-Angela
