Picasso etchings

One of my clients owns a pair of etchings by Picasso.  They are both
depictions of female nudes.  She has not yet given me the dates.
Both are signed and numbered by the artist.

I am trying to identify the signature medium.  In both etchings, the
signature color has apparently changed.  For the first etching, the
signature is now a faint red.  The owner claims that it was a much
darker red when she originally bought it many years ago.  The
signature on the second etching has no color at all.  The signature
is visible as a tan discoloration with a hard, glossy surface.

Does anyone have any ideas what this material might be?

Jayne Girod Holt


                                  ***
                  Conservation DistList Instance 16:46
                 Distributed: Friday, January 31, 2003
                       Message Id: cdl-16-46-021
                                  ***