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G'day folks, i live in Australia and i have recently downloaded some glaze recipes, Cone 6, from ceramic arts, can some one please tell me if Gllespie Borate is the sam e as Gerstley Borate? I need to make a stable Clear glaze for an electric Kiln firing to cone 6. Any help appreciated

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G'day folks, i live in Australia and i have recently downloaded some glaze recipes, Cone 6, from ceramic arts, can some one please tell me if Gllespie Borate is the sam e as Gerstley Borate? I need to make a stable Clear glaze for an electric Kiln firing to cone 6. Any help appreciated

 

 

Well how are you? I am not sure if Gillespie is the same as Gerstley Borate. But if a recipe calls for Gerstley Borate I use 3195 frit instead because Gerstley has a problem with crawling. You can replace them one for one most the time. You might try "Digital Fire" they have a great data base of Materials and a great glaze cal.

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G'day folks, i live in Australia and i have recently downloaded some glaze recipes, Cone 6, from ceramic arts, can some one please tell me if Gllespie Borate is the sam e as Gerstley Borate? I need to make a stable Clear glaze for an electric Kiln firing to cone 6. Any help appreciated

 

I searched the clay art archives and found this post from 2003

Personally, I use Gillespie borate as a 1:1 substitute for Gerstley. In one

instance, I have added a small amount of borax to boost the boron content,

but that is an anomaly. In my raku glazes, Gillespie works just fine. Same

for all my cone 6 glazes. Sometimes, I come across a recipe calling for

Frit 3134. I'll try both 3134 in one test, and Gillespie in another test.

Both work very well for me.

Hope this helps

Mark

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I, too , have used Gillespie Borate as a substitute for gerstley in my Raku glazes. I actually likes it better in a few glazes but that could be just a difference in location, firings, kilns, etc.

Here is the Clear ^6 I use with stains. It works really well with crimson Mason Stains. Please forgive the formatting. This is a nice smooth satin to shiny clear.

 

Sue Hintz Clear 6^ reworked by Ron Roy

 

 

Cornwall Stone 33.5

G200 22

Whiting 18

Gerstley Borate 10

EPKaolin 5.5

Silica 11

Bentonite 2

 

Marcia

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thanks for all your answers, a few of you talk about frit 3134 I actually use 4110 for my cone six glazes, and i have used the base with no colour to produce a clear finish, though you have to be careful not to put it on thick as that can turn it opaque! as to the gillespie borate until i saw the recipes i had never heard of it or seen it in any of our local pottery supply places here in Oz.

For those of you in the US you have a clear glaze over there from Duncan Ceramics, which is a little miracle glaze in that you can fire from Low to High Fire with no running and its called Diamond Clear. But is very expensive by the time it is imported to OZ.

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thanks for all your answers, a few of you talk about frit 3134 I actually use 4110 for my cone six glazes, and i have used the base with no colour to produce a clear finish, though you have to be careful not to put it on thick as that can turn it opaque! as to the gillespie borate until i saw the recipes i had never heard of it or seen it in any of our local pottery supply places here in Oz.

For those of you in the US you have a clear glaze over there from Duncan Ceramics, which is a little miracle glaze in that you can fire from Low to High Fire with no running and its called Diamond Clear. But is very expensive by the time it is imported to OZ.

 

 

Gillespie Borate is identical to Gerstley Borate on paper. The problem is that Gerstley is the most inconsistent material we potters use. People in industry laugh when they hear that we use it. It was originally mined for the roofing tile industry, who didn't require the level of consistency that we need in glazes. Potters started using it because it was a cheap source of non-soluble boron, and had great suspension qualities. As they worked through the mine, the formula of Gerstley would change, and everyone's glazes would look different. There was even a year or two in the 80's when it got so bad that a lot of potters stopped using it. If you search for formulas for Gerstley to put into your glaze calculation software, you'll find a dozen different answers.

 

Gillespie Borate is based on one of those formulas, and can be used as a direct substitute. However, most people find that it is a bit stronger than Gerstley, meaning you might need to use about 3% less in any given recipe. The good news is that, as a frit, it will be 100% consistent from batch to batch. So once you get it worked out in your recipe, you'll never have to reformulate it again. And it's cheaper than Ferro frits!

 

If you compare the formulas of Gillespie Borate and Ferro 3134, you'll see there are some significant differences:

 

Gillespie Borate

11.8% SiO2

1.7% Al2O3

24.5% B2O3

23% CaO

3.9% MgO

3.77% Na2O

0.45% SrO

0.01% K2O

30.9% LOI

Ferro 3134

10.3% Na2O Soda

20.1% CaO Calcium

23.1% B2O3 Borate

46.5% SiO2 Silica Oxide

 

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