I TOTALLY agree with Dave's last statement. Actually I don't
really > understand why jewelers continue to use vulcanized molds
at all. I continually shake my head when there is discussion abut
I use both. If I want a mold to last forever and it’s a complicated
piece that is difficult to cut, I prefer traditional vulcanized Gold
Label rubber. I like it because it is so tear resistant, I can
strrrrrrretch a thin little bit quite far before I cut it and it
won’t tear. Or I can pull a bigger piece through a smaller hole and
not have a tear. Or cut a corkscrew, so it unwinds out of a tight
spot. You really can’t do that stuff with the current RTV compounds.
The shrinkage is the only real issue I have with it and if you plan
ahead it’s easy to deal with.
So if I have something that I need a bullet proof mold of, something
for a line that will be reused many many times for instance, I use
the traditional rubber. If I just need to use the mold a few times
or if it’s a relatively simple mold to cut, I use the RTV.