Hobbies And Interests
Significance
Photographs of any type and material, from early Dagerreotype to today's digital prints, are subject to deterioration when the complex chemical process that created the images comes in prolonged contact with light, humidity, environmental pollutants or simply human contact. The chief culprits of decay in photographs are acid and lignin in wood-based paper products, which cause discoloration and disintegration over time.
Prevention/Solution
Proper storage using acid-free supplies such as paper, albums and boxes can prolong the life of those school photos, vacation memories and family images. These products are advertised as "acid-free," "lignin-free," "photo-safe" or "archival quality" and can be found in hobby, craft, office supply and stationery stores as well as through craft and paper product websites.
Archivists recommend storing photos in acid-free paper or plastic sleeves which are laid flat in boxes also made from an acid-free material. If photo albums are preferred, they should be manufactured from materials that are safe for long-term storage of photographs.
Science
Acidity is measured by pH, a scientific formula that ranges from 0 to 14 with a pH of 7 considered neutral. Pure distilled water is considered neutral. A pH of less than 7 is acidic and a pH higher than 7 is called alkaline or basic. For example, battery acid has a pH of 0 and vinegar's pH is 3. On the other side of the scale, milk of magnesia has a pH near 11 and household bleach approaches a pH of 13.
Acid-free paper and storage products are treated with a buffering agent to neutralize the processing and naturally occurring acids. The resulting products have a neutral pH ranging from 7 to 9.5 and won't damage photographs during storage. Museums, libraries and universities have successfully used acid-free products to protect historical documents as well as photographic images.
History
Hercules Inc., a Delaware chemical company, in the 1950s developed the process to create acid-free paper products. But it wasn't until 1984 that standards were developed for the use of acid-free paper, mainly in library materials. Today, amateur and professional photographers, scrapbook hobbyists, museum curators and the U.S. Library of Congress use acid-free products for their photograph storage and preservation.
Considerations
Not all acid-free products provide the same protection for photographs. For prized collections, images that already have some damage or photos that require special treatment and care, look for products that are marked as "photo-safe" or "archival quality."