Removing bat urine stains from painted wood

I am working on a painted timber charity board (originally 18th
century, with subsequent repaintings) which has been kept since its
construction in an extremely damp parish church, with a significant
resident bat population. A thick layer of accumulated dust and grime
was removed relatively easily using first dry cleaning methods and
then a 15% tac solution, but white staining--which I believe is
caused by bat-urine--has proved impossible to clean with all the
usual solvents. Does anyone have any suggestions?


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                  Conservation DistList Instance 18:34
                 Distributed: Tuesday, January 25, 2005
                       Message Id: cdl-18-34-015
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