the all-seeingeye Threats to Photographs: Chemical

This photograph is made from a negative which was heavily damaged in storage-by a combination of an envelope with a high sulfur content, and by the presence of residual processing chemicals.

Photographs are susceptible to attack by a number of chemical agents. These include sulfur compounds and acids, as well as peroxides and other bleaching agents. Some act against the paper base of the photograph, and others against the image itself.

There are general and local environmental threats to photographs. The mechanism which produces acid rain can also have an impact on photographs. The byproducts of combustion-whether it be wood, coal, oil, or gasoline-can, in the presence of moisture, create damaging acids in the fabric of paper. There isn't much you can do about this unless you can afford a climate-controlled vault.

Local environmental conditions are something you can control. Photographs should be kept away from sources of chemical harm. First, avoid other materials which suffer from "inherent vice". This is a simple as acid-free envelops and boxes. This precaution will take care of as much as 75% of the problem. One of the single most critical things is to get rid of any wood storage boxes or picture frame backings. Many species of wood contain compounds which can wreak havoc with paper. Ideally, storage cabinets should be of enameled steel-and they should not be airtight.

Unfortunately, rubber cement has been one of the most common glues used in photo albums for the past century. Rubber cement breaks down and liberates any number of noxious chemicals that damage photographs. It should be avoided. Where you have album pages with rubber cement, you should give serious thought to removing the photographs so that the damage will at least slow down.

Plastics have a somewhat checkered history when it comes to photograph storage. Some are good, some are very bad. Even the good ones can contribute to surface damage if enough humidity is present.

So called "magnetic" album pages, common in the 1980's, are a major problem. The "temporary" adhesive becomes quite permanent with time, and it will eventually leave brown stripes on the photographs which bleed through to the front. Which leaves us with the issue of what to do with all those albums you've inherited. Do you remove the photographs from the pages-which be damaging them, or do you leave them intact for their historic/sentimental appeal? There is no hard and fast answer to that question. If possible, I'd leave them together, and store them under the best possible conditions to slow deterioration as much as possible. The only exception would be the magnetic pages.

Wood grain and saw mark patterns on the back of a photograph framed entirely in wood.

One source of chemical threat to a photograph is built into the photograph itself. This situation is sometimes called "inherent vice". Poor quality paper (unusual in photographs but not unheard of) sometimes contains manufacturing residue which can hasten its deterioration. Additionally, photographic papers are subjected to a fairly caustic series of processing steps, which, if not completely rinsed out, can also accelerate deterioration. These chemicals can be removed, but the process requires specialized skills, so it is unadvisable to attempt on your own.

The existence of inherent vice has implications for how you store photographs. If there is one bad apple stored with the good apples, it can contaminate the rest. Except in the most extreme cases, storing images separately in their own acid-free envelope, and keeping them dry and cool is sufficient to keep any effect limited to the bad apple.