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Subject: Microfilm deterioration

Microfilm deterioration

From: Michael McCormick <aa683>
Date: Sunday, June 5, 1994
First, I'd like to thank all those people who responded via email to my
inquiry regarding the bluish microfilm (Conservation DistList 05-12-94).
The comments were quite helpful.

Next, I thought I'd summarize those responses for the DistList. There
was net agreement on the several points.

The tonal shift from blue to pinkish purple were unanimously seen as the
most positive identifier of the film as diazo. Generally it was agreed
that the dye couplers of the image were breaking down, causing the

Also, everybody agreed on the vinegar syndrome.  Of course, if the image
is going to fade, it really is less important if the base is going to

Finally, a couple of respondents noted that the formation of the brown
tone in the film base is also an indicator of acetate base.

Fortunately, there's already a 35mm silver of these records, which can
form the preservation collection.  Unfortunately, over the years, the
County Recorder has purchased TWO sets of the 16mm, one diazo, one
silver.  Three sets of one records series amply demonstrates the need
for records management!

Anyways, once again, thanks to all for your most helpful responses.

Michael McCormick

                  Conservation DistList Instance 7:88
                   Distributed: Monday, June 6, 1994
                        Message Id: cdl-7-88-003
Received on Sunday, 5 June, 1994

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