Storing Ektachrome slides

I am in charge with a project for preservation of transparency films
(10,000 Ektachrome 13 x 18 cm 64T, 100 Plus, Duplicating). We are
building an air-conditioned storage.

These are the actual conditions of the slides: Most of them are 20
years old. The old storage was not air conditioned and they have
been preserved to 24 deg. C and 50% RH. Despite of this fading is
just a little perceptible.

I'm using the James M. Reilly's "wheel" for color. We have used-up
approximately 80% (20 years) of the life of the film (25 years at 24
deg. C and 50% RH). So there is only about 20% left. If I should
decide to move today the films in an air-conditioned storage (e.g.
16 deg. C and 40% RH) we have a life of 125 years. 20% of 125 is 25
years.

The "time out of storage" is relevant, because slides are used
frequently. Using the time-out of storage table (the other side of
the wheel) 120 days out of storage in 16 deg. C and 40% RH would
reduce 125 years to 45 years. Slides have already spent 80% of its
life at 24 deg. C and 50% RH, there is 20% of its life left. 20% of
45 is 9 years. If I switch the vault today to 16 deg. C and 40% film
will last 9 years before fading occurs.

We can't freeze the Ektachrome films because we don't have
preservation copies, but only working copies, and low
temperatures--under 13 deg. C for instance--will cause the
condensate phenomenon during the passage from the storage to the
office.


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                  Conservation DistList Instance 21:31
               Distributed: Wednesday, November 21, 2007
                       Message Id: cdl-21-31-027
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