An artifact that is common across almost all households these days are historic photographs.
The most common types of historic photographs found in family collections are silver gelatin (black and white) prints popular from the 1890’s and still produced today, and chromogenic colour prints popular from the 1940’s. Both of these types of prints tend to deteriorate in a characteristic way. Silver gelatin prints contain silver molecules that can migrate over time towards the surface of the image, producing a mirroring affect. This shiny-metallic appearance tends to concentrate in darker areas, such as shadows. Silver-gelatin prints also tend to yellow and lose their highlights over time. Chromogenic colour prints contain three dyes that interact to produce colour images: Cyan, Magenta and Yellow. These dyes are inherently unstable and will change and fade. Cyan tends to deteriorate first leaving a yellow or red tinged to photographs. The above are all examples of chemical deterioration resulting from reactions that are almost impossible to halt or reverse, but chemical reactions can be slowed down by minimizing exposure to heat, moisture, and light. Keeping your historic photographs in a cool (no attics), dry (no basements), and dark (in a box) environment will do wonders to prolong the life of your special moments captured on film.
Often photographs are kept in frames, albums or scrapbooks for long periods of time. Popular in the 1970’s and 1980’s are photo albums with sticky or magnetic pages. These albums can be very detrimental to photographs as the chemicals in the adhesive can interact with the image layer and cause it to discolour or stain. The image layer may also stick to adhesives on the album and peel off when you attempt to remove photos. Archival quality albums where photos slide in and out of the page are the best option for long term preservation. When framing photographs make sure there is a gap between the glass and the image layer, for example use matte board for framing works of art, so the image layer doesn’t stick to the glass. When scrapbooking tape or other adhesives are not recommended for use directly on photographic prints, consider investing in self-adhesive photo corners to hold photographs in place. These can be purchased at most craft supply stores. When shopping for photograph display and storage supplies look for features like acid-free, archival quality, or inert, these supplies may be a bit more expensive but they will help your photos last for many generations to appreciate. For further information on identifying and caring for historic photographs visit the Graphics Atlas, created by the Image Permanence Institute.