I recently bought two Chinese soup spoons. One is plain white glased porcelian and the other is unglazed or matte glazed ceramic of some type. Can I use them to slump with? If so is there any special preparation?
Yes you can use glazed ceramics as moulds. But you do have to prepare them for use by removing or roughening the glaze enough to accept shelf primer as a separator between the ceramic and the glass. Ensure there is a draft (no vertical sides). I have a note on found moulds at: http://glasstips.blogspot.co.uk/2010/10/found-moulds.html