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?  ...

This type of construction and/or repair is typical of Tang Dynasty
horses. I suggest you first look at

    Strahan, D. and Boulton, A.,
    "Chinese ceramic quadrupeds:construction and restoration", in
    The Conservation of Far Eastern Art, Contributions to the Kyoto
    Congress, John Mills, Perry Smith and Kazuo Yamasaki editors,
    IIC, 1988.

As to the removal of iron stains from unglazed earthenware, I have
had very good success using 10% oxalic acid.  If the fragments are
small, you can presoak them in deionized or distilled water, then
transfer them into the oxalic acid solution, or use the solution in
a poultice. Leave for 10 minutes, rinse and repeat if necessary.
Thorough rinsing and soaking in deionized/distilled water is then
required.

Stephen Koob
Conservator
The Corning Museum of Glass
One Museum Way
Corning, NY 14830
607-974-8228
Fax: 607-974-8470


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                  Conservation DistList Instance 16:29
                 Distributed: Friday, October 25, 2002
                       Message Id: cdl-16-29-003
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