Metal printing plates

Eric Alstrom asks for information about the corrosion on some metal
printing plates.  It is very likely that the plates are zinc, and
that having been stored for many years in wooden boxes, the
corrosion product is a basic zinc carbonate.  Becoming translucent
when wet and going white again when dry sounds very like corrosion
products I have seen on other zinc artefacts. This is quite tricky
to remove, as the encrustations are hard and the metal is fairly
soft and easily deformed, so I do not think that mechanical removal
would be easy.  I hesitate to suggest this without seeing the
plates, but I wonder whether an electrolytic process would be
feasible, particularly as there is a large number of plates to
treat.

Dr Barry Knight
Head of Conservation Research
The British Library
96 Euston Road
London NW1 2DB
+44 20 7412 7229
Fax: +44 20 7412 7658


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                  Conservation DistList Instance 17:32
                  Distributed: Monday, October 6, 2003
                       Message Id: cdl-17-32-010
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