Soot on wall painting

We need to clean a ceiling painted with tempera that is actually
covered with a thick lay of soot. The soot was recently provoked by
a fire in which different synthetic materials were burnt. The
problem is that the colors of the painting are sensitive to water
and so it is difficult to use water-base solvents. Does any body
have any suggestion to give us?

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                  Conservation DistList Instance 12:45
               Distributed: Wednesday, November 18, 1998
                       Message Id: cdl-12-45-008
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