Marking RC prints

Does anyone have any suggestions for the best material to use to
write accession numbers on RC photographs (and slick-surfaced
digital prints)?  Pencil does not seem to be suitable as it tends to
indent the paper, and will not necessarily effectively mark the
paper.

Carolyn Murphy
Paper Conservator
Queensland Art Gallery
Australia

                                  ***
                  Conservation DistList Instance 12:46
                 Distributed: Monday, November 23, 1998
                       Message Id: cdl-12-46-016
                                  ***