Earthenware ceramic

I am currently treating a Tang dynasty cream coloured earthenware
figure of a horse.  The figure has previously undergone extensive
restoration including the insertion of approximately 4mm diameter
ferrous dowels into each of the legs; each leg having been broken in
at least three places.  In addition the feet of the horse have been
adhered to a rectangular wood base for display and a layer of cream
toned plaster has been applied over the surface of the legs and base
to disguise the breaks and repairs.

The object recently came to our lab as the repairs had failed and
the horse is required for display.  The feet remained attached to
the wood base, but had broken at the knees from the rest of the
horse.  The corrosion of the ferrous dowels had resulted in further
breaks in the ceramic and the plaster layer had been damaged to
partially reveal the underlying ceramic material. I have since
removed the remaining plaster layer to reveal the ceramic and have
removed the feet from the wood base.

However, removal of the plaster layer has revealed ferrous staining
to the cream coloured earthenware.  Has anyone any experience with
removal of ferrous stains from unglazed earthenware ceramic?  Is
this possible?  Also it would be ideal to remove the dowels from the
ceramic as they are causing considerable damage, both with staining
and through expansion.  Any helpful suggestions as to how this could
be achieved would be much appreciated,

Helen Privett
Conservator of Objects
National Gallery of Victoria
Melbourne, Australia


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                  Conservation DistList Instance 16:28
                 Distributed: Tuesday, October 22, 2002
                       Message Id: cdl-16-28-014
                                  ***