Removing carbon ink from paper

I have an unusual request. A client has a 19th c. stock certificate with a
20th c. commemorative rubber stamp that is not wanted. Use of the typical
solvents on a suction device has removed a trace of the ink (dye). An
electric eraser removed about 50% of the carbon ink that remained. Does
anyone have any suggestion as to another approach to remove the remaining
carbon? There are about ten certificates with two stamps on each, so
mechanical removal would be too time consuming--too costly.
Thanks for any help you can offer,

Bill Minter

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                  Conservation DistList Instance 11:18
                  Distributed: Friday, August 22, 1997
                       Message Id: cdl-11-18-010
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