Carved coal object

Emma Herrity <emma.herrity [at] broxtowe__gov__uk> writes

>Could anyone recommend the best method of cleaning a carved piece of
>coal about 100 years old - should it just be dusted when needed?  It
>is currently in a display case and I wondered if there would be any
>environmental problems with adding other objects, e.g. silver pocket
>watches to the case.

I would guess that dusting with a soft brush would be safe--coal can
be soft and brittle so damage to carved details must be avoided.
Coal contains a fair amount of water so it is sensitive to the
ambient relative humidity: it could crumble if desiccated, or if the
RH varies greatly.  Coal also contains sulphur in various chemical
forms (hence SO2 pollution from burning coal) so it would definitely
be unwise to place silver objects in the same case.

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


                                  ***
                  Conservation DistList Instance 19:5
                  Distributed: Saturday, July 9, 2005
                        Message Id: cdl-19-5-007
                                  ***