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Food Safe Glazes


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#1 jammy43

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Posted 12 February 2014 - 05:52 PM

I'm looking for the food safe guidlines for glazes.  I'm in the process of mixing up glazes from scratch and need to know what to lookout for.

Currently  i have a base that is:

EPK            30

Frit 3110     20

Gristle Boriate 50 



#2 Norm Stuart

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Posted 12 February 2014 - 06:21 PM

I'd suggest reading "Mastering Cone 6 Glazes" regarding the need to test glazes for leeching.

 

This spreadsheet has the Food Safe Clear Liner Glaze they use as an example.

 

http://home.roadrunn...stuart/MC6G.xls



#3 Marcia Selsor

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Posted 12 February 2014 - 07:01 PM

I agree. Mastering Cone 6 glazes is a great book for understanding glaze chemistry and understanding your glazes.
BTW I think you mean Gerstley Borate.
Marcia

#4 neilestrick

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Posted 13 February 2014 - 01:09 PM

I assume this is a cone 6 glaze? If you put this glaze up against a limit formula, you'll see that it's quite low in silica, which can affect the food safety of the glaze. The only way to know for sure whether or not a glaze is food safe is to have it tested by a lab. However, with knowledge of glaze formulation you can formulate glazes that are likely to be food safe, which will save you a great deal of time and money before shipping tests off to the lab. Invest in a good glaze formulation book like Mastering Cone 6 Glazes as Marcia suggested above, or Clay and Glazes for the Potter by Rhodes, of Ceramic Spectrum by Hopper.


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#5 JBaymore

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Posted 13 February 2014 - 01:41 PM

Look around the "In The Studio" and "Technical" forum sections. This subject comes up a lot and there is a lot of good general information hiding in the threads already in place. Use the forum "search" function.

 

best,

 

........................john


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Professor of Ceramics; New Hampshire Insitute of Art

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