Food Safe Glazes

[john autry]

I am searching for a "food safe" glaze data base. Is there one? Or are there just certain guide lines, exclusions of materials, that will make all glazes inherently safe? I thought this stuff would be all over the interweb, but I only see bits and pieces. Perhaps I'm looking in the wrong places. Any thoughts appreciated. I fire to cone 6. Thanks, john

[Brenda Neall]

I would start with the book Mastering Cone 6 Glazes by John Hasselberth & Ron Roy (see link on the right). All the safety testing has been done for you and going forward you can use the bases to develop your own versions.

[john autry]

john autry said:Thanks Brenda. I'll put this book on my "Get" list. ja

[George Lewter]

This network has a lot of information on the concept of "food safe" in established discussion topics. Have you tried the search box in the upper right corner? The issue is more ambiguous than you might think, and the term itself is problematic in that it implies an absolute. 

[john autry]

George, I'm starting to understand the problem, little by little. This here "food safe" pottery issue is complex AND ambiguous.  I might as well be searching for recipes for safe automobiles or safe guns. There are so many ways to look at what makes things safe and unsafe. I get it. You have to rely on your own information, research, and experience. And  absolute is illusive, at best. What is safe to eat today, may prove to cause cancer tomorrow.   Search box, yeah, but I didn't find what I was looking for. Now I think I know why. Thanks for your reply.  john

[Norm Stuart]

Knowing what is in your raw materials is important to glaze chemistry as well as food safety. The product MSDS (Materials Safety Disclosure Sheet) can be helpful, but only in determining the ingredients manufacturers are required to list.

Safety is indeed relative.

Many potters claim they would never consider using a potentially toxic ingredient like barium as an ingredient in their glazes, yet these potters purchase commercial clay and glazes which routinely includes barium carbonate to prevent salt scumming. The quality control rep at the clay or glaze supplier will be happy to explain why the level of barium carbonate they use is safe, yet this is a world away from the absolute prohibition many of their potter customers think they apply in their studio.

Many brightly colored glazes, which formerly used lead now use the less toxic but more costly metal bismuth, which is not disclosed on glaze labels. Still many potters would never knowingly use bismuth in their own glazes yet have oral bismuth salt in their home in the form of Pepto-Bismal and Kaopectate. In fact pepto-bismal, or bisqued pepto-bismol tablets, can often be the least expensive way to source bismuth for glazes.