Microfilm
Integrity Test & Audit
Cellulose
acetate replaced nitrate as a film base in the 1940’s. At the time, it
was called “safety film” because it was comparatively more stable and
less flammable than its predecessor. Acetate was used as a film
base almost exclusively until the early1980’s, when it was replaced by
stable polyester.
Regrettably acetate is not chemically stable and will deteriorate under
normal conditions, slowly at first and then with accelerated speed (with a vinegar-like smell in the final
stages). The legacy of acetate is large parts of film
collections on an unstable film base and it is a serious one. The
accepted method to slow the deterioration rate is cold storage
(5-10oC at 20-30% humidity) – this buys time to assess more
interventional options such as duplicating, scanning or
re-filming. However, there is not much time left to take urgent
action when the film is in the "vinegar state". Should a
library inadvertently wait too long the film layer carrying the optical
information will tear and split off from the film base.
What happens at normal room temperature:
In average room storage conditions—in the presence of moisture, heat
and acids— the cellulose acetate base can break down. The
chemicals combine with water to form acetic acid, the compound that
gives vinegar its familiar taste and odour. The result:
The film base loses its dimensional
stability and becomes brittle. The microfilm may curl, shrink and
buckle, degrading or destroying the preserved images.
Good News
The good-news is that film produced after the mid-1980s is not prone to
vinegar syndrome though some manufacturers did not stop production of
the triacetate film until 1994. That’s when film manufacturers began
migrating to a rugged polyester plastic base. These polyester
microfilms have a minimum life expectancy of 500 years when properly
processed and stored.
Vinegar syndrome is usually the sign that there is something
catastrophic happening. It’s a clear sign that your vital
microfilm records are in danger. Contact Gosford Micrographics
and we will evaluate your archival microfilm library, and put forward
an immediate solution.
Click here for more information,
consultation or a quote