For more than a century, people have enjoyed the ability to capture a special moment in time with a photograph. People enjoy seeing pictures of their parents and grandparents when they were young. Many take it for granted that their children and grandchildren will someday enjoy the pictures they take today.
However, you probably have experienced yellowing, cracking, and fading of some of your photographs. Still others are destroyed or simply lost. Although some photographs last for generations, none of them are immune to the effects of time. This pamphlet provides tips that can help you preserve your photographic treasures.
What a Photograph Is Made Of
Photographs are made-up of several layers of materials. The top layer contains the image suspended in gelatin (purified animal protein). It is called the emulsion layer. This layer is coated on to a base layer of photographic paper of film. A mid layer of adhesive is used to make the emulsion stick to the base.
The materials used to form the image depend on the type of photograph. The image for black and white photographs is made up of light-sensitive silver salts (silver halides).
Color photographs and slides are made up of dyes instead of silver deposits. Like all dyes, those used in photography fade and/or change color over time. Since most of the photographs taken today are made in color, researchers continue to work on dye stability. With proper care you can expect your color prints to last for decades, but in general, they do not preserve as well as black and white images.
Causes of Deterioration
Many factors can contribute to the deterioration of photographs. since photos are made up of layers of material, damage to any one layer can ruin the image. Often, it is a combination of factors causing the damage. The following are some of the most destructive influences.
High temperature and relative humidity - These factors by themselves are damaging and together they are the most destructive factors that affect photographs. Temperatures above 70 F and relative humidity above 60% for long periods should be avoided. Daily, drastic temperature changes (such as occur in an attic) and continuously damp areas (such as basements) should also be avoided. At the other extreme, very low humidity, under 25%, is also damaging. It causes the emulsion layer to crack and the base material to curl.
Because the emulsion layer is composed of organic materials (the gelatin), heat and high humidity promote the growth of mold and fungi on it. The gelatin also softens and becomes sticky as it begins to retain moisture. Heat and humidity also make base materials deteriorate quickly. Cold temperatures (refrigeration) are preferable, especially for color photos, but only if humidity can also be controlled. Standard refrigerators have a high relative humidity and are NOT a good place to store photographs. Air-conditioning used with a dehumidifier helps control the effects of temperature and humidity when refrigeration is not an option.
Residual processing chemicals - Damaging chemicals can be left on photographs if they are not processed correctly. In black and white photographs, these chemicals are made up of sulfur and silver compounds which react with the silver of the image to turn a yellowish brown color. Over time, the silver compounds can become silver sulfide which will not only discolor the photograph, but also fade the image. Residual chemicals also increase the effect of external influences such as heat and humidity. For these reasons it is important that you have your film developed by reputable professionals or, if you develop your own, that you follow processing procedures precisely as the manufacturer suggests.
Air pollutants - All kinds of airborne substances can be damaging to photographs. Those people living in cities with high pollution levels will find this especially true. Oxidizing gases containing sulfur compounds, paint and varnish fumes, cleaning agents (chlorine and ammonia), tobacco smoke, auto exhaust, salty sea air, and dust are some of the most troublesome pollutants. Photos should not be stored in areas where these pollutants are present. For example, avoid closets that also contain cleaning products and remove photos from rooms freshly painted with an oil based paint for at least a month (latex paint is safe).
Nitrate based film - This type of film base was common in the early 1900's. It is relatively unstable and decomposes rapidly.. It is also flammable and in large quantities is considered a fire hazard. During decomposition it produces oxidizing gases such as nitric oxide and nitrogen dioxide. These by-products of decomposition also speed up the decomposition process and are damaging to other negatives and photographs that may be stored near them. If possible, have pictures on nitrate based film converted to newer, safer film. At the very least, store nitrate based film away form your other photographs.
Ultraviolet light - Direct sunlight and fluorescent light can be very damaging to the image on a photograph. This is particularly true of the dyes in color photos which will fade rapidly when exposed to light. For all types of photographs, it is best to avoid prolonged exposure to direct sunlight and to use ultraviolet filters on fluorescent lights. tungsten lights are much safer than fluorescent lights.
Mishandling - Much of the damage to photos comes from the way we handle them. Always try to avoid touching the emulsion surface. Some other obvious things to avoid are bending, cutting, or scratching photographs. Less obvious dangers are such common household items as ink, staples, paper clips, glue and tape. These products all contain substances harmful to photographs. The next section (Proper Storage Methods and Materials) will list products safe to use with photographs.
Natural Disasters - There are a few things you can do to protect your photographs from flood, fire, and other natural disasters. Storing them up off the floor is relatively simple and can help tremendously in case of minor flooding. Storage in an enameled steel file cabinet can prevent photographs from being crushed and offers some safety from water and fire damage. You may want to consider a safe deposit box for extremely valuable photographs. It is also wise to give copies of special photographs to relative to avoid having them all in one place in case of a disaster.
Proper Storage Methods and Materials
In addition to avoiding the conditions mentioned in the previously section, using specialized storage methods and materials help prolong the life of photographs. The storage environment is very important. Heat, relative humidity, light, and air pollutants should be maintained as close to acceptable levels as possible. The two places photographs are most often stored, attics and basements, do not provide the best conditions.
When storing prints and negatives, a general rule is never store them in contact with one another. Prints and negatives can stick to each other. Also, any print with residual processing chemicals could affect the prints around it as it begins to decay. Each should be stored in a separate paper or plastic enclosure. If you have mounted prints, be sure to place a sheet of paper or plastic (interleaving sheets) between them during storage. The prints and negatives within their enclosures can be stored in acid-free storage boxes on a shelf or in enameled steel file cabinets.
If you prefer the convenience of a photograph album, take great care in choosing it. Ironically, many mass produced photograph albums are made from photo-damaging materials. Albums can be safe if made of proper materials.
Below is a list of do's and don'ts when choosing storage materials and locations. Also, the next section lists the names of two catalogs where you can order the proper materials. You should also be able to find these materials in photographic supply stores.
- Do use special photographic paper, envelopes and mounting board (museum board) to store and mount your pictures. These paper products should be acid-free and have a high alpha-cellulose content.
- Do use archival linen tape, filmoplast tape, polyvinyl acetate gelatin adhesive, mounting boards with overlay sheets, or, for newer prints, dry mounting tissue.
- Do store photographs in acid-free storage boxes, stainless steel or enamel-coated steel cabinets and frames, and porcelain frames. When framing, be sure to use acid-free matting between the print and the glass to provide ventilation and prevent the print from sticking to the glass.
- Do store prints in the coolest, driest area possible and try to maintain a fairly constant temperature.
- Do use special sheets, bags, and envelopes made of acrylic plastics, cellulose acetate, polyethylene or polyester.
- Don't use normal paper envelopes or construction paper to store or mount your pictures.
- Don't use scotch tape, paste, rubber cement glue (white, synthetic, vegetable, or organic), staples, or paper clips to secure your photographs to mounting materials.
- Don't store photographs in contact with ordinary cardboard, wood (especially if varnished), or polystyrene (Styrofoam). Be conscious of these products when choosing frames, photograph albums, and storage containers.
- Don't store prints in hot attics or damp basements. These areas are also prone to daily, drastic temperature changes which are damaging to prints.
- Don't use polyvinyl-chloride plastics. Also known as PVCs, these plastics are often found in ordinary, mass produced photograph albums.
Additional Preservation Techniques
Another method for preserving your photographs is to have copies made of them while they are still in good condition. It is also wise to display these copies instead of the originals.
For black and white photographs, toned prints tend to be more stable. The toning process changes the metallic silver of the image to a form that is more resistant to oxidizing gases. The toning is performed during the developing process and results in the photograph having a brownish or purplish tone to it. This process is not recommended for old prints.
For color prints, consider having black and white negatives and prints made since these tend to last longer. There is a method which produces black and white separation masters. These separate the different layers of color into a black and white format which can be recombined and color at a later time if desired. However, this procedure is costly and difficult.
As you can see, there are several relatively simple things you can do to help your photographs last longer. By carefully choosing the mounting materials, storage materials, and storage location for your photographs, you can preserve memories for generations to enjoy.
Bibliography
- Eastman Kodak Company. conservation of Photographs. Rochester, NY, 1985
- Keefe, Laurence E., Jr. and Inch, Dennis. The Life of a Photograph. Boston: Butterworth Publisher, 1984
- The Polaroid Corporation. Storing, Handling and Preserving Polaroid Photographs: A Guide.., 1983
- Weinstein, Robert A. and Booth, Larry. collection, Use and Care of Historical Photographs. Nashville: American Association for State and Local History, 1977
Sources of Safe Storage and Display Materials
- Light Impressions, P.O. Box 940, Rochester, NY 14603-0940, (800) 828-6216
- Archival Quality Materials, University Products Inc. P.O. Box 101, 517 Main Street, Holyoke, MA 01041, (800) 628-1912
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