Removing bat urine stains from painted wood

Eimear O'Connell <oconnee [at] hotmail__com> writes

>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?

Understanding the chemical nature of bat excreta and the method by
which deterioration takes place would be a good start. In many such
cases, the white bloom is not a residue of the urine, but a
deterioration product of the of the art work. Basic cross-sectional
analysis should clarify this. Does the statutory permission obtained
for the treatment of the painting allow original material to be
removed? (if you are in a C of E church, I presume there is a
Faculty).  English Heritage undertook a great deal of research on
this subject and the results are published in "Bats in Churches,
guidelines for the identification, assessment, and management of
bat-related damage to church contents". You can get this as a PDF at

    <URL:http://www.english-heritage.org.uk/
        Filestore/publications/pdf/free/bats_church.pdf>

    **** Moderator's comments: The above URL has been wrapped for
    email. There should be no newline.

Tobit Curteis
Tobit Curteis Associates
Cambridge
UK


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                  Conservation DistList Instance 18:36
                 Distributed: Sunday, January 30, 2005
                       Message Id: cdl-18-36-008
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