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Most microfilm created prior to 1980 has a backing made of acetate plastic. These acetate films are subject to an additional kind of degradation
called "vinegar syndrome". All master microfilm created today uses a polyester plastic backing. Under proper storage conditions, today's film has a 500 year Life Expectance
(LE). The older acetate films have no more than a 100 year LE. Since some of this film is now over 60 years old, we are beginning to see more and more vinegar syndrome degradation.
When the backing on acetate films begins to degrade it releases acetic acid. This is exactly the kind of acid that makes vinegar smell and taste like vinegar. The release of the acid into the air in the
film's canister begins a rapidly accelerating process of film degradation that can only be stopped by duplication onto modern polyester backed film. (This degradation is slowed considerably in our vault
through the use of molecular sieves.)
The major complication with vinegar syndrome film is that the film begins to "bow and curl". In advanced stages the film will be so wavy that if it is taken off its storage reel it can not go back on because
its volume doubles. This film cannot be accurately duplicated on most silver duplicators. Heritage owns one of a handful of specially built silver duplicators that holds the bowing and curling master film
solidly against the new silver duplicate film with a fiberglass cloth belt at high pressure. In this way even the curled portion of the master film is held in direct contact with the duplicate film for a very
high resolution duplicate.
We are the only commercial lab in the world to use this technology.
The slightly higher cost of our silver duplicate film is far less than the cost of losing part of your history forever to curled master microfilm. |
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