H&G Cornwall Stone
Hammill & Gillespie, a supplier of specialty clays and minerals, has found a substitute named H&G Cornwall Stone which can be used as a replacement in most glaze formulas. It is always best to test any new material, however, before committing to large scale production.Click here for the article from Ceramics Technical by Jeff Zamek about the differences and similarities of the original and the new: https://www.sheffield-pottery.com/v/vspfiles/downloadables/HG-Cornwall-Stone.pdf