Poultices for cleaning marble

I've been reading about alot of different cleaning methods for
marble.  I'm looking for different poultices because I want to
remove some ingrained dirt/graffiti on marble.  Unfortunately, the
marble is somewhat "sugary" but I'd like to avoid pre-consolidation.
Can anyone relate their experiences, good or bad, on the subject?

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                  Conservation DistList Instance 12:2
                   Distributed: Friday, June 12, 1998
                        Message Id: cdl-12-2-006
                                  ***