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gerstly borate

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#1 clay lover

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Posted 28 January 2013 - 09:36 AM

While I am fine with mixing the glazes I use, I am not so sharp about understanding all the intermixed effects of different ingredients.

I have been having some pitting issues, and have been through the standard treatments, soaking longer, thinner application, firing hotter, bisquing hotter, no changes. Then a potter suggested that the gerstly borate in the glazes might be the issue.

Do any of you smart glaze folks have anything to offer on this subject? What percentage of GB can a glaze have before the pitting problem comes up? Is the substitute for it, Gelespie B, equivalent in the mix, or will it produce a different glaze?

#2 spadefootclay



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Posted 28 January 2013 - 10:00 AM

I've used up to 40% gerstley without pitting. You might try substituting ferro frit 3134 and see how the glaze reacts -- good luck.

#3 TJR


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Posted 28 January 2013 - 02:44 PM

Gerstly Borate is not your issue in my opinion. Some low fire glazes have 75% gerstly and work fine.
Have you considered dust particles? I sand my pots, then I bisque. After the bisque there is dust on the pots. I dip them in a 5 gallon pail of water. Let dry over night. Then you are ready to go.

#4 JBaymore



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Posted 28 January 2013 - 06:57 PM

A glaze recipe here along with a picture or two would be a HUGE help in a diagnosis. :)src="http://ceramicartsda...ult/smile.gif">



John Baymore
Adjunct Professor of Ceramics; New Hampshire Insitute of Art

Former Guest Professor, Wuxi Institute of Arts and Science, Yixing, China

Former President and Past President; Potters Council



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