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Subject: Diazo microfilm

Diazo microfilm

From: Charles Stewart <cstewart>
Date: Sunday, March 5, 1995
Michael McCormick <aa683 [at] cleveland__Freenet__Edu> writes

>I have inspected a record series on diazo that has, essentially, been in
>dark storage in a bank vault since its creation in the mid-1970s. It
>shows approximately a 50% density loss.  Therefore, light exposure must
>accelerate the process, but does not initiate it.

These are deep waters!

It doesn't especially surprise me that the films faded in dark storage.
We know that dyes on film bases can dark-fade, as well as light-fade.
Henry Wilhelm's work in studying color film deterioration shows that. My
point in response to Mr. DeBolt was simply that subjecting these
materials to the powerful, specular illumination provided by the
projection lamps and condensers in microfilm readers must surely hasten
the process.

Vinegar syndrome I associate with cellulose acetate bases, especially
the earlier ones, and I didn't know this type of material was used for
diazo in the mid-seventies.  Have you tried tearing a bit of non-imaged
film (i.e., leader/trailer) as a crude test to be sure it's acetate?
Again, I think it's Image Permanence Institute which has looked into
vinegar syndrome and, by way of solving your puzzle, it would be good to
send them (or somebody else who functions as a research lab in these
matters) a sample for evaluation.  My concern with ammonia fumes and
outgassing is directed more toward the possibility of
oxidative-reductive deterioration in silver films, in the labs where
both types are made, and in storage.

If you think you are losing your diazo records to fading, then you'll
probably want to have new duplicates made from the masters, if they can
be located.  If not, it may be possible to create a silver copy from the
diazo, depending on how far gone the things are.  We've had varying
degrees of success here in duping diazo-to-silver, but if you can come
out with something usable by this process, the product can at least be
made and stored for permanence.

C. Stewart

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Received on Sunday, 5 March, 1995

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