I have been making some rubber molds with the Castraldo Gold
material. The metal masters were cast in Manganese Bronze. The
pieces need to be in bronze and that is what I had on hand. They
will be clasps for heavy wool capes for the period reenactment. I
found that there is a stain on the rubber at the point of contact
with the metal master. This stain keeps the wax from releasing from
the mold, even with the silicon release spray. I finally nickle
plated the masters and made new molds. These release just fine and
have no stain on the rubber.
I am curious as to what is causing the stain on the rubber? It is a
brown color. I notice that I get the same stain from the sprue
formers which may be brass. Is the copper in the alloy causing this
reaction with the rubber?
No more metal masters in bronze, one lesson learned.
I am also open to suggestions on a bronze choice.
When you have a Siberian Husky, one of the first things you learn is
that the weather is NEVER to cold not to walk the dog.