i got molds made of wax carvings a few years ago,,, is there any
way to have no shrinkage of the silver casting that is made
it’s a bit tricky since to start with, even if the mold itself had
no shrinkage, the wax you inject into it will shrink on cooling, so
it will tend to be slightly smaller than the original.
There are methods you can use to reduce the shrinkage, though.
Casting into a hotter mold will give a little less shrinkage, since
the investment expands as it gets hotter, so the metal is cast into a
slightly larger mold. But as that cools, there is then shrinkage
again of the mold, which can slightly compress the softer metals like
silver. But it’s still less shrinkage than you get with a cooler mold
temperature. However, the hotter mold temp on casting will then also
increase the risk of some types of porosity or other casting
Another, perhaps more effective method, is to use a dental
crystobalite investment. These investments have a higher thermal
expansion rate than the usual jewelry investments, since they’re
intended to compensate for metal shrinkage in casting in order for
cast dental inlays to still fit the cavity prepared in the tooth.
This still doesn’t help you with the shrinkage of the wax when
injected, but it can make up much of the difference. The dental
investments, because of the high thermal expansion, work better with
small casting flasks and a flask liner to cushion some of that