I've been making jewelry for over 30 years, but something that
has always driven me nuts is mold making.
I have vulcanized molds for small runs for ever.
As a response to my inane intro to a problem that I am having, let
me continue with a further intro to my problem and a question or two
As I was saying, I have worked with model makers and casters that
would make molds of everything with little or no care as to the
results of a quick mold production. As a result, crappy models
result. This is not a big problem with very small runs of rings that
may be touched up, but in the case of say, precision diamond links,
this can be disastrous.
I am currently making a diamond necklace with about 80 links
totalling 14 1/2 inches. These are little more than bezels with some
engraved features. I no longer have the patience to try to repair
each and every link. I want a good clean shiftless and full model. I
would like to be able to cast, clip, grind down the sprue and tumble
with a minimum of labor. Normally, this requires me to make numerous
molds with my fate being relegated to the forces that be. In my case
this really is an art. I would like to turn this into something more
of a science.
Currently, I use silicone or other RTV molds. I have made vulcanized
rubber molds for about 30 years. I get equal or better results with
RTVs and am currently using I currently use a hand pumped injector,
but just invested in a pressurized mold injector to eliminate
variable pressures. Mold slippage seems to be a problem with a lot
of molds. I cut or form locks in the molds with formers. Incomplete
injection is a problem that I hate to deal with. Increased pressure
and relief cuts tend to help the mold to breath, but can result in
I don't think that I can name all of the problems associated with
attempts to make decent models from rubber molds. I would really
appreciate hearing how some of you have overcome some or even all of
the problems associated with precision models.