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Subject: Nitrate negatives

Nitrate negatives

From: Doug Nishimura <dwnpph>
Date: Tuesday, October 20, 1998
Since my comments appeared in Conservation DistList Instance 12:27
regarding the possible cause of higher mirroring on nitrate
negatives around the watermark, a number of people contacted me
about the possibility of the problem being chemical watermarking. I
have to admit that no one really believed that Light Impressions
would allow chemical watermarking to be used with their "archival"
papers, but it was a possibility.

I have since contacted Dennis Inch at LI to check on their
specifications and he has assured me that they use mechanical
watermarking for just that reason. They had decided to use the
watermark to distinguish the "buffered" version from the
"unbuffered" several years ago. It was possible to print on paper
enclosures to indicate which type of paper was used, but not for
interleaving papers. I've worked with Dennis for a number of years
and I know that he knows the materials (and production of them) from
end to end.

It is interesting that this phenomenon has not been observed in
other collections, although it should be very slow when the
negatives are stored under good conditions. My recommendation for
people putting negatives into cold storage is to package and store
immediately. In theory, the magnitude of the problem will depend on
the condition of the negative. As with acetate base, there tends to
be a fairly long induction period with nitrate followed by
accelerating deterioration.

Douglas Nishimura
Image Permanence Institute

                  Conservation DistList Instance 12:38
                Distributed: Thursday, October 22, 1998
                       Message Id: cdl-12-38-002
Received on Tuesday, 20 October, 1998

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