Determining the Source

Photographs can be made out of a variety of materials: silver, iron, glass, paper, plastic, salts, dyes, and gelatin, just to name a few.

Eras of Photography:

• 1840-1855 Daguerreotypes, Salted Paper Prints
• 1856-1890 Tintypes, Ambrotypes, Albumen Prints
• 1889 Nitrate Film
• 1920 Acetate Film
• 1950's Polyester Film

Storage

• Store photos and negatives away from each other in envelopes or folders made of stable plastic film or acid-free paper. Place the envelopes in acid-free boxes and don't pack them too tightly.
• If storing photos on edge, make sure they are supported with PAT-tested boards so that there is not any excess space that would cause the photos to slump into a curve.
• Avoid storing photos in contact with draft paper, glassine envelopes, mounting board with high wood-pulp content, rubber cement, or glue.
• When storing photos flat in boxes, lay no more than twenty in a stack. The photos on the bottom could be damaged by too much weight.
• If negatives do not lay perfectly flat, or they have an obnoxious odor, deterioration has begun. Remove deterioriating materials immediately.

Care

• Handle photographs, negatives, and slides only by the edges and avoid touching the image. Wearing cotton gloves is a good idea.
• If you encounter large numbers of deteriorating negatives, make sure the room has good air circulation, and wear protective clothing and/or a respirator mask. The fumes from these can be toxic.
• Try to label photographs on the backs of frames or on album or storage pages. If necessary, use a soft, No. 2 pencil to write lightly on the back.
• Keep photos and negatives out of the reach of pests.

Glossary

acid-free tissue - In the course of time most tissue paper will become acidic and brittle with age. The acidity will transfer to adjacent objects causing these objects to become weaker and possibly discolored. Acid free tissue papers are specially processed to remove such contaminants. An 18 pound weight paper is useful for quilts, coverlets, and the storage of other flat textiles. For stuffing or interleaving, a lighter 12 pound paper is better. This lighter acid free paper is also known as "laminating tissue."

conservator - persons who periodically examine objects, document their condition, and, if necessary, treat and repair them to protect collections over time.
For more information or to locate a professional conservator, visit The American Institute for Conservation of Historic & Artistic Works.

muslin - a thin plain-weave cotton cloth used for curtains, sheets, and dresses

PAT test (photographic activity test) - a test that predicts possible interactions between photographic images and the enclosures in which they are stored. Boxes or other types of enclosures that hold several images, even if those images are in envelopes or sleeves, should be tested too. Many of the harmful chemicals in poor-quality enclosures can become airborne and, over time, work their way to the photograph.

PVC pipe - a lightweight, durable, and waterproof plastic pipe used for plumbing

polyethylene bags - flexible, extremely tough, and chemical-resistant plastic bags commonly used as sandwich or freezer storage

ragboard - board made from cotton and contains no wood (lignins). Little pulping or purification is required because cotton is the purest natural form of cellulose. Rag board is also called Museum Board, is acid-free and meets the standards set by the Library of Congress for museum quality matboard. It is available with or without buffering.

unbuffered - containing neither alkaline nor acid