Stabilizers for hydrogen peroxide

I am looking for advice about stabilizing hydrogen peroxide for
general use as a local bleaching agent in our paper conservation
lab. We have recently bought unstabilized 30% hydrogen peroxide
(Fluka / Sigma.) We chose the unstabilized product over the commonly
available sodium stannate (Na2SnO3) stabilized product, having been
advised that tin carbonate can easily form and be deposited in the
paper. Apparently, in an acidic environment, it would not be
difficult for the tin to form other salts which would be colored
compounds. I had been using the stannate stabilized solution to
perform lead sulfide conversion on a gouache painting with an acidic
support and did witness an unexpected color (light mauve) forming
instead of white lead sulfate--perhaps from the explanation given
above. It was not like the brown tones I saw forming from incomplete
conversion to sulfate.

>From what I understand, it is best to use a stabilized form to help
prevention of radicals through sequestering those metals that would
promote decomposition. I have not been able to find hydrogen
peroxide stabilized with acetic acid or sodium silicate, which would
not form colored compounds. Other available products in the market
are stabilized with phosphates or acetanilide. I am considering
stabilizing our stock by adding sodium silicate and magnesium
sulfate in a sodium carbonate solution per Helen Burgess'
instructions in her article titled, "Practical Considerations for
Conservation Bleaching."

    Burgess, Helen
    "Practical Considerations for Conservation Bleaching."
    J.IIC-CG 13(1988): 11-26.

We are interested in general feedback. Has anyone experienced
long-term problems with stannate stabilized treatments? Does anyone
know of products on the market with good stabilizers or do you
stabilize your own stock? Or, maybe it's not unreasonable to use an
unstabilized product if the paper artifact has been pre-washed and
will be well rinsed after local bleaching?

Jessica Silverman
NEA Fellow in Paper Conservation
Conservation Center for Art and Historic Artifacts
264 S. 23rd St.
Philadelphia, PA 19103
215-545-0613
Fax: 215-735-9313




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                  Conservation DistList Instance 22:67
                   Distributed: Friday, May 15, 2009
                       Message Id: cdl-22-67-014
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