Reed Bovee 2014-02-10 10:52:35
When you open a can of archival film and smell “vinegar,” you’re actually smelling the cellulose triacetate film base decomposing. The smell doesn’t mean that the film has deteriorated significantly, but it does mean acetic acid is leaching out of the film base and breakdown has begun. Chemical degradation of film base is an irreversible process. Acetate base—safety film—has been around since the 1940s and ’50s, when it replaced unstable (flammable) nitrate base. It took scientists another thirty years to understand that acetate film is also unstable. What Is Vinegar Syndrome? Vinegar syndrome can cause cloudiness on The image, much of which, surprisingly, can be cleaned off. When you follow recommended film cleaning procedures, the white powdery material can be removed and the odor becomes less pronounced. The acid also can react with the gelatin in the image layers and the dyes (in color film), causing the emulsion to soften and the image to deteriorate. Over time, vinegar syndrome also can make film sticky, causing one layer to adhere to the next and resulting in defects such as ferrotyping. In severe cases, it can pull bits of the emulsion off the base. The film also can shrink—and at different rates—with the outer edges shrinking more than the center. The result is a kind Of buckling effect, with individual frames becoming cupped or curved. Eventually the film becomes too brittle to handle; you’ll find yourself opening the can to discover that the film has transformed into powder. Steps to Minimize Effects Although freshly processed acetate film put immediately into cold storage can last Hundreds of years, most films aren’t handled that way. In typical real-world storage conditions, vinegar syndrome can start after only a few years. Although it can’t be stopped, it can be slowed down. Here are ten steps you can take to minimize its effects: 1 Open the can and look at the condition of the film. Film in rusted cans should be repackaged in clean archival packaging. 2 Remove films from metal reels with spokes. Over time, vinegar syndrome will cause metal reels to rust and film to shrink and twist. This will make it more difficult to remove from “spoked” reels without edge damage. 3 Rewind film on plastic cores (www.kodak.com/ motion). A lab core with a 3-inch diameter helps to “relax” the film. Machine-winding—with proper alignment and even tension—is recommended. 4 Put an A-D strip (www.imagepermanenceinstitute .org) in the can, even if you don’t smell vinegar. The strip absorbs acetic acid and its color scale quantifies the level of film degradation from blue (minimal) to bright yellow (advanced decomposition). 5 Put desiccants—such as molecular sieves (www.kodak .com/motion)—in the can. They absorb moisture and help to contain vapors. The Kodak site provides guidance for the number of sieves to be used, based on the size of the reel. 6 Lay the film cans flat—never on their vertical edge— and no more than twelve inches high. 7 Store the film in a cold, dry environment. Storage in an environment with a temperature of 45° to 50°F (7° to 10°C) and no more than 20 to 30 percent relative humidity can significantly improve film’s stability. Films with advancing vinegar syndrome can be stabilized and decay can be postponed when they are stored in subfreezing temperatures. 8 Inspect the films at least every few years. Look for physical changes in condition, check the A-D strip for color changes, and replace the desiccants, which don’t last indefinitely. Increase the inspection frequency if any vinegar odor or film deterioration is observed. 9 Wear white cotton gloves when inspecting archival films. Wearing gloves protects hands and prevents skin oils or any other contaminants from transferring to the film. 10 If possible, separate the films in different stages of decay. Keep as much physical distance as possible between cans with vinegar syndrome and those without. The syndrome is contagious; cans stored together can advance degradation in all. The bad news: Most archival film is on acetate base, which means that most archives are affected by vinegar syndrome. But there’s also good news: By taking a few basic steps and maintaining proper storage conditions, archivists can extend the life of acetate films— even those starting to deteriorate—for many years to come.
Published by Society of American Archivists. View All Articles.
This page can be found at http://www.bluetoad.com/article/Ten+Steps+to+Control+Vinegar+Syndrome/1630213/194014/article.html.