Earthenware ceramic

Helen Privett <helen.privett [at] ngv__vic__gov__au> writes

>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.  ...
>... 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?  ...

The suggestion of S. Koob to get more information about the making
of Tang horses seems to me a good idea. Although you are probably
dealing with iron dowels used to restore the legs you could consider
the possibility the iron are an armature baked with the clay.

The presence of iron armature in Tang animals is mentioned in the
article of Strahan and Boulton.I restored a few years ago a Tang
horse and found rests of mineralised iron armatures in the four
legs, on an X-ray we could see the iron armature were running in a U
shape from one leg to the other through the body of the animal. A
similar case was found  by L. Bruno in a horse at the Brooklyn
Museum.

I realise this would not solve the problem of cleaning the rust
stains but it could bring the presence of iron in a different light.

Isabelle Garachon
Conservator of ceramics, glass and stone
Rijksmuseum
Hobbemastraat 25
1071 xz Amsterdam
+31 20 6747234


                                  ***
                  Conservation DistList Instance 16:30
                Distributed: Wednesday, October 30, 2002
                       Message Id: cdl-16-30-008
                                  ***