Pigeon droppings

I am a third year conservation student. For my dissertation I am
carrying out a feasibility study on cleaning a section of limestone
floor in a very prominent part of a cathedral. The floor is covered
in black stains left by pigeon droppings which have impregnated the
stone.

>From a review of the literature I can find only two mentions of
cleaning methods for such stains; John Ashurst recommends using a
sponge or poultice with 1,1,1-trichlorothane and a UK company have
produced an enzyme product to clean bird droppings from masonry.

If cleaning is focused on the individual stains the floor will be
covered in white circles. If the whole affected area is cleaned you
would then have a prominent area that is much cleaner than the rest
of the floor. Any suggestions?

Paddy Connor
University of Lincoln
UK


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                  Conservation DistList Instance 18:39
                 Distributed: Friday, February 18, 2005
                       Message Id: cdl-18-39-047
                                  ***