Photographs are wonderful, mysterious things. Yet we have become so accustomed to them that we take them for granted. 1999 marked
160th anniversary of public introduction of photography. Prior to 1839 you could not see what distant places truly looked like, or see yourself as you appeared when you were younger. Most people didn't know what President of United States really looked like, or King or Queen of England. Oh sure there were pictures, artists drawings and paintings, but they were all interpretations -- even most faithful representations were influenced by style, medium and mind of artist. Along came invention of photography, and all that changed overnight. With every picture you take, you are freezing a moment in time; capturing a view that can never be exactly same again. You may have a closet full of such frozen moments, or just a few rolls from your last vacation. If you want to be able to enjoy those moments far into future, you need to take some care in handling and storage of those images. If you have family photos handed down from earlier generations, you have a responsibility to future generations to pass them on in as good condition as possible.
When taking care of older photographs it helps to know something of process by which they were made, but it not essential. If you would like to learn more about 'Identifying and Dating Old Photographs' there is considerable information available. In practice, all photos need to be protected from same dangers. Light is enemy number one. Chemical degradation is another problem, and much less easy to deal with. And of course you must protect them from physical damage, be it curiosity of children or fury of storm, flood or fire.
LIGHT
Photographs are made by action of light on a specially treated chemical surface (at least they were before digital imagery was invented, but more about that later ...) Little wonder then that even after they are fixed into a stable image, photographs can still be affected by light. Bright light will cause photos to fade. Actually, all photographs are fading at all times, but light greatly accelerates process. The degree of fading depends on type of process used to create image, how well it was processed, and other factors. As a general rule, color photos fade faster than black and white.
Of course you have to expose photos to light to view them, and what good are they if they are never seen? But you should be careful to store them in light-proof boxes. Pictures you hang on your walls should be thought of as disposable -- don't hang original if it is a family heirloom -- make a copy and hang that. Avoid placing pictures where they will be in direct sun.
CHEMICAL DEGRADATION
When pictures fade from sunlight it is really a form of chemical degradation, but there are other factors that can contribute to this process. If pictures were not properly processed when they were made, they have more damaging chemicals on them, and will suffer effects of chemical degradation much faster than properly processed images. If you are having copies made, or prints from new photos that you want to last well into future, you can have them archivally processed to ensure fewest possible damaging trace chemicals will remain on print. Old prints can be re-processed to remove chemicals, but that process should only be attempted by professional restoration experts.
Another source of chemical degradation is paper (or on mounted pictures, cardboard print is mounted on) used in making prints. If paper is too acidic, it may fall apart with time, disintegrating slowly from within. There are sprays available that can be used on back of photos to slow this process.
Photos can also pick up deleterious chemicals from their environment, air around them, other pictures, or material they are stored in. To ensure long life, store your pictures in safe materials designed for archival storage. Never use those so-called magnetic photo album pages that are sticky -- that sticky surface is made of chemicals that will destroy your pictures.
