Lead corrosion

I'm currently working on a large wall relief (8x10 feet) by Robert
Morris. The piece is constructed of sheet lead over a substructure
of steel and particle board. It has been in a closed plywood
container with white styrofoam for the past twenty years and is now
covered in a tenacious layer of white corrosion (lead formate I
think). Initial tests show the corrosion to be only very slightly
soluble in concentrated acids (sulfuric and hydrochloric) and
completely insoluble in most everything else (including hot water
and sodium EDTA poultices).

I've tried localized electrolytic reduction using a 9V battery with
a lead solder electrode and sodium bicarbonate electrolyte and
although I get a reaction it is very very slow and not particularly
effective.

I don't want to try to immerse the piece for longterm electrolytic
reduction because of the vulnerability of the substrate and the lead
is too fragile to remove.  Has anyone tried ion exchange resins on
lead corrosion? Are they effective? I'd rather not use an
air abrasive process because of the toxicity factor.

The other question is that the storage cases will need to be
replaced and I'm wondering if anyone knows a supplier of large scale
ventilated polypropylene cases or cases which do not outgas
corrosive chemicals.

Susan White, White Conservation Services


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                  Conservation DistList Instance 17:57
                  Distributed: Tuesday, March 2, 2004
                       Message Id: cdl-17-57-023
                                  ***