Identifying chrome tanned leather

Cor Knops <knops [at] xs4all__nl> writes

>Is there a *simple* way to determine whether there's chrome involved
>in the tanning of this leather?

The following test will show up chrome, even if it is present in
small quantities.

Cut a very small piece (a few millimeters square) of the offending
leather and place in a small crucible such as a teaspoon and heat
over a cigarette lighter.  Heat to an extent where the residual
carbon is also burnt-off. If chrome is present, even in low amounts,
the resulting green ash will indicate this.

However, it is also worth noting, that other mineral tannages also
give similar working characteristics as a chrome retanned leather,
such as Aluminium and Zirconium.  The above experiment would not
show that these minerals are present. Kind regards,

    **** Moderator's comments: Thanks also to Michael Maggen who
    sent in similar information

David M. Lanning
J. Hewit & Sons Ltd., London
+44 181-965 5377
Fax: +44 181-453 0414

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                  Conservation DistList Instance 12:14
                   Distributed: Friday, July 31, 1998
                       Message Id: cdl-12-14-005
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