New here - hope I'm doing this right! I have a question about cores for ceramic shell casting. I teach a foundry class, so I am no newbie. Generally for hollow pieces I cut out a section or make sure the piece is designed so that the center will build up a shell and be able to dry properly. But, I am now doing some foundry work for another artist out of my studio of some small animal figures. These are a little too big to cast solid (though I can if necessary), but a little too small for a large enough opening to allow the shell to make a strong core -- soooooooo.....I have been looking into using some sort of core material.