I have the same problem with a .925 stamp. Also, what is the trick
to stamping without marring/flattening the other side?
This might take longer, but it does a better job of preventing
marring on the opposite side of an item being stamped. This works
well for slightly thin items that might deform outwards from the
stamping. It also works well for hard to hold or position items.
Melt a good blob of dopping wax (setter's shellac works, too) on a
piece of wood that is stable and flat-bottomed. I just use a piece
of wood the size of a bench block. Then press your item into the
dopping wax and cool in place. If heat is not a problem with your
piece, gently heat the piece and/or the wax so that the piece is
gripped by the dopping wax. You may have to hold the piece with a
tweezers until the wax cools a little to prevent it from sinking too
deeply or tipping awkwardly. It is important to secure the piece in
the wax so that the area to be stamped is level, making it easier to
position and strike the stamping tool. After the wax is cool, stamp
your piece. The dopping wax serves as a customized holder and it
provides support and resistance against deformation to the metal
being stamped. You avoid flat spots and bumped out spots on the
opposite side. I like dopping wax because it doesn't give as much as
chasing pitch. (NOTE: If you stamp with the dopping wax still warm,
you won't achieve the hard, rigid support and you may get a raised
welt on the opposite side.)
After stamping, gently heat and lift out the piece. Be careful not
to scratch your piece when lifting it out of the dopping wax. Clean
off with denatured alcohol.
Another trick with the dopping wax: Sometimes I have to stamp on
bails that can't be slid onto a tiny horn anvil without marring the
inside opening or on the cross bars of hollowed-back earrings that
would cave in without support. I fill the hollow areas that need
support with pitch and then sink piece to an appropriate depth into
the pitch. I cool everything as usual, then stamp, remove and clean.
I always stamp before doing any stone setting so I don't get gunked
up stones or have to address heat or solvent sensitivity issues.