Stamp pad ink

I have been asked about the stability of ink found on proprietary stamp
pads. Archeologists often stamp accession/registration numbers on their
sherds as it saves time over traditional crow quill pen and permanent
ink techniques.  Does anyone know what the ink put on pads usually is
and how stable it might be. Has there been any testing of this type of
ink?  And if it's a horribly unstable method of marking artifacts,does
anyone have any suggestions for a comparable method that would be more
stable?

Thanks for your help.

Jessica Johnson
Texas Memorial Museum

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                  Conservation DistList Instance 7:56
                 Distributed: Monday, January 31, 1994
                        Message Id: cdl-7-56-003
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