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Glaze Toxicity And Functional Ware Questions


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#1 Pam S

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Posted 11 January 2011 - 08:19 PM

I'm a community taught, amateur potter who is delving into the glaze making world. I inherited a large, and I mean large store of glaze supplies from our local recreation center when they discontinue the art programs. :0( I know the basics of the raw material safety but I am concerned about ingredients used is some of the glaze formulas in the finished/fired functional ware I make. I also inherited numerous glaze formulas but only a few were labeled "not food safe." I know to keep away from anything lead based or containing cadmium, barium is also questionable, but what about nickel and cobalt? Two more questions, what ingredients not to use for functional ware, and can you use non food safe glazes on the outside of a functional piece if the interior is glazed with a food safe glaze? Thanks for your patience with the neophyte.

"Saving just one dog won't change the world, but it surely will change the world for that one dog."


#2 bciskepottery

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Posted 11 January 2011 - 11:07 PM

Invest in a copy of John Hesselberth/Ron Roy's book Mastering Cone 6 Glazes. That will give you a good start on understanding how to prepare durable and safe glazes, as well as how to test for these characteristics. The book also has a great brown glaze recipe (Waterfall Brown). Some raw materials, like lead, you want to avoid. However, materials like cobalt need to be used in the right proportion to remain food safe, durable. Ogther books that cover the topics of raw materials thoroughly are John Britt's book on high fire glazes -- his intro material on glazes is applicable to all glazes, not just cone 10, and Robin Hopper's book on color spectrum. For most beginner's, the Hesselberth/Roy book is a terrific starting point.

#3 Marcia Selsor

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Posted 12 January 2011 - 09:02 AM

My friend inherited a very large quantity of glaze ingredients from the family of a deceased potter. They family was going to
be charged a lot of money to dispose of the ingredients legally. Ingredients had to be tested as hazardous waste material.
It was a better idea to pass them on to interested potters.
You would be wise to get Mastering ^6 Glazes by John Hessebreth and Ron Roy as mentioned about. It is a great book for someone in your position and will give you the tools you need to make food safe glazes.

Marcia

#4 Pam S

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Posted 12 January 2011 - 11:32 AM

Oh boy! An excuse to buy a book! LOL! Thanks! I'll look for it today!

"Saving just one dog won't change the world, but it surely will change the world for that one dog."


#5 Pat Franz35

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Posted 13 January 2011 - 01:34 PM

I would suggest that you make darn sure that you have a chemical/poison control number on your glaze before I would tell anyone that the glaze I made from scratch is food safe.

Otherwise promote the pottery as a collector item for decreative purposes only.


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#6 Pam S

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Posted 14 January 2011 - 09:10 PM

Pat, would you be so kind as to clarify your post for me? Most of the potters I know make their own glazes and sell their works both as functional or art pieces.

"Saving just one dog won't change the world, but it surely will change the world for that one dog."





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