browsed through a book today that I hadn’t looked at for a long time.
It’s “Indian Jewelry Making” vol. 2 by Oscar T. Branson, copyright
1979. It has a section about cuttlebone casting. Before pouring the
metal, the interior of the cuttlebone was coated with a thin solution
of borax, water glass and water. The photographs showed the
difference between using this mixture and not. It seemed to really
preserve the mold through more than one pour. I have no idea of what
water glass is. I know that it used to be used to preserve eggs
before refrigeration and that 's it. I have seen it on drugstore
shelves in the distant past. I wonder if there are harmful fumes
released when it is heated? John, how about an answer?