Tobacco stains on painting

I have a friend who has a Hudson River School painting which has
been sullied for many years by tobacco smoke. There does not appear
to be a varnish present and is thinly painted.

The grime does not respond to common solvents as expected but is
only very slightly soluble in saliva. If my friend tries to clean
the painting with saliva it will take a ridiculous amount of time to
complete the job.

I have found various cleaners designed specifically for "cleaning
off tobacco smoke from paintings," but these look to be
heavily-solvent based and I'm sure must work by solubilizing the
upper paint layer and taking the grime with it.

When I was at Winterthur, I remember Richard Wolbers working with
various enzymes for cleaning paintings, but since this isn't my
field (I'm an objects conservator), I really haven't kept up with
the research in this field.

Does anyone know of a safe, possibly enzymatic, commercially
available product to clean tobacco smoke off of paintings? Any
suggestions would be most appreciated,

Susan White
White Conservation Services


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                  Conservation DistList Instance 22:38
                Distributed: Saturday, January 10, 2009
                       Message Id: cdl-22-38-019
                                  ***