Identifying chrome tanned leather

Here is a somewhat belated answer to Cor Knops' enquiry about chrome
tanned leather.

Over the past few years I have been working with Nancy Odegaard
Conservator at the Arizona State Museum, on a publication of spot
tests used in conservation.  These are not new tests  but we have
tried to apply some of them in new ways.  One example is a test for
chrome metal that uses a 1% solution of diphenylcarbazone in
ethanol.  We had good success in distinguishing the chrome in chrome
tanned leather with this test.  A positive shows up as a violet
color.  You need to dissolve a small sample of the leather in
concentrated nitric acid on a blotter before adding the
diphenylcarbazone.  (It goes without saying that one must always
take the appropriate precautions when working with any acids or
other chemicals.)

Scott Carroll
Conservator
National Museum of the American Indian
Bronx, NY

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                  Conservation DistList Instance 12:15
                 Distributed: Wednesday, August 5, 1998
                       Message Id: cdl-12-15-006
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