Has anyone try tried casting with a tufa stone?
I have way back in the 70’s. The process is, as far as I know, developed by Southwest Native American craftsmen. Two pieces of tufa are ground perfectly flat on one face. One of the pieces has the design etched deeply into one face and a spru port cut into it. The pieces’ faces are then blackened with an acetylene or candle flame. The two halves are wired together and molten metal is poured. There you have the very basics of the process. Used mostly in heavy silverwork, like bracelets, by Navaho craftsmen.