Stains on creamware--addendum

Susan White <smwhitewhite [at] aim__com> writes

>I am currently working on a piece of English creamware with a lead
>glaze from around 1790.  The piece has numerous brownish spot stains
>on the rim of the ceramic, as well as on the foot. ...

I am still having a difficult time removing a very tenacious stain
from a creamware mug.  I initially began by alternating 3% hydrogen
peroxide with ammonia, poulticing the stain using cotton wool.  The
stain responded, but slowly and then stopped.  It seemed that the
ammonia solubilized the stain, moving it from the rim of the mug
farther down the sides, and the hydrogen peroxide, of course,
lightened it.  We stopped the ammonia poultices, fearing further
movement of the stain and then tried a proprietary hair bleaching
product which contained 12% hydrogen peroxide and a sequestering
agent.  This sped up the bleaching of the stain, but after two
weeks, the stain still remained.  We were finally able to obtain 30%
hydrogen peroxide at reasonable cost from Museum Services, and
although the stain has dramatically lightened with three weeks of
immersion, it still can be seen.  Does anyone know whether, if we
leave the piece immersed in the hydrogen peroxide long enough,
whether the stain will eventually disappear?

Susan White
White Conservation Services


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                  Conservation DistList Instance 24:53
                   Distributed: Monday, May 30, 2011
                       Message Id: cdl-24-53-006
                                  ***