I recently torch fired some pmc paper pendants. They were then
tumbled for two hours in new metal shot. They came out looking
great but some the thinnest peices then broke when trying to add
jump rings. What did I do wrong?
There are several possible issues here. First, you don't give details
on your torch firing method. You need to hold the entire piece at a
glowing orange color for a minimum of 3-5 minutes. 10 minutes would
better. Second, a single layer of pmc sheet is very thin and,
unless reinforced, usually too thin to withstand the wear and tear it
will get from a jump ring. Chances are your problem is a combination
of the two.
Sheet type was designed to do origami with and a flat piece of fired
and polished sheet is too fragile for most purposes. Best uses are to
fold it, layer it, weave it, and apply it over itself or other
pieces. If you want a single layer for an extra light weight earring,
you can do that, but you will have to reinforce (double) the hole
where you put the jump ring.
You should check out the metalclay list
(groups.yahoo.com/group/MetalClay) for more on metal
Mary Ellin D'Agostino, PhD