Richard Schenz on sun 11 mar 01
I have a teacher & friend who is a production potter - with no computer.
She asks the question, where can she have her glazes tested for safety.
Some of her glazes are commercial products and she is not too concerned
about them. However, she mixes several from scratch and would like to check
them out.
We would appreciate any information that anyone can give us.
Thank you,
Richard Schenz
In Sunny Tucson
rschenz@earthlink.net
John Hesselberth on sun 11 mar 01
Hi Richard,
Go to my web site and look at the section on Glaze Stability. You can
print off copies of instructions on having glazes tested there. One test
she shoud do on all glazes (including commercial ones) though is to soak
half a test coupon or cup in vingar for three days. If the color fades
she has a very unstable glaze. If the sheen changes it is a borderline
glaze in my book and might be worth further testing or might not. I would
certainly never use a glaze like that on the inside of a pitcher or
casserole dish. The best glazes will show no visible change at all. Your
friend may be surpised at how unstable some of her commercial glazes are.
When a commercial glaze manufacturer says their glazes are "food safe"
that doesn't always mean they are stable. There are varying definitions
of the term food safe making it a nearly meaningless term. After vinegar
testing she can confirm or quantify the results with professional leach
testing depending on what is in the glaze.
Find my web site at
httP://www.frogpondpottery.com
Feel free to contact me off list if you need more help.
Regards, John
Richard Schenz wrote:
>I have a teacher & friend who is a production potter - with no computer.
>
>She asks the question, where can she have her glazes tested for safety.
>Some of her glazes are commercial products and she is not too concerned
>about them. However, she mixes several from scratch and would like to check
>them out.
>
>We would appreciate any information that anyone can give us.
>
>Thank you,
>
>Richard Schenz
>In Sunny Tucson
>rschenz@earthlink.net
>
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