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Runny Cone 10 Glaze


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I am a high school teacher and I found a beautiful commercially produced Turquoise glaze that tends to run, a lot!  I have never relly gotten in to the chemistry of glazes.  I have always used prepared commercial glazes.  Simple, easy to mix and cheap. 

 

My question is, what can I add to the glaze to reduce the amount of running?  I believe that the running is a result of firing the glaze to too high of a temp.  However, if I fire to a lower temp to keep the Turquoise from running, the other colors will not fully mature.  With so many students, I don't have the capacity to do a firing of just the Turquoise glazed projects.

 

My little research says that by adding China Clay to the glaze it will reduce the runnyness (not sure if that's a word).  I also saw that Spodumene will raise the melting temp as well.

 

Any help is greatly apprecioated.

 

Brian

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Spodumene is a powerful flux, where did you see that it would raise the melting temp? I would not have thought that. 'Lithia is a very powerful flux, especially when used in conjunction with potash and soda feldspars. As one of only a few natural lithium source materials, spodumene is a valuable component in glass and ceramic/enamel glazes (Li2O reduces thermal expansion, melting temperature and viscosity of the glaze melt).'

 

Adding a little china clay might work.

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E.P.K. in 3% increments. Test on a vertical tile.

Do you have the recipe?

I have other Turquoise glazes that don't run. I could give you the recipe for one of those.

Tom.

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E.P.K. in 3% increments. Test on a vertical tile.

Do you have the recipe?

I have other Turquoise glazes that don't run. I could give you the recipe for one of those.

Tom.

Its a commercially made glaze.  So I don't have the formula for this glaze.

 

I'll try adding some Kaolin.  Thanks for the help.

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I am a high school teacher and I found a beautiful commercially produced Turquoise glaze that tends to run, a lot!  I have never relly gotten in to the chemistry of glazes.  I have always used prepared commercial glazes.  Simple, easy to mix and cheap. 

 

My question is, what can I add to the glaze to reduce the amount of running?  I believe that the running is a result of firing the glaze to too high of a temp.  However, if I fire to a lower temp to keep the Turquoise from running, the other colors will not fully mature.  With so many students, I don't have the capacity to do a firing of just the Turquoise glazed projects.

 

My little research says that by adding China Clay to the glaze it will reduce the runnyness (not sure if that's a word).  I also saw that Spodumene will raise the melting temp as well.

 

Any help is greatly apprecioated.

 

Brian

 

I have a commercial ^6 red that runs like crazy.  Last time I used it, I added something, which improved it greatly.  Only trouble is, I know I didn't write down what I added, but my memory is saying it was alumina. Something, somewhere told me to add a "refractory" to the clay to slow it down and make it stick to the pot.  

 

As a non-chemical-understander, I'd say, try a few tests with various additives, but make sure they are vertical tiles, not horizontal.  And always use catchers/cookies under the tests.

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Chilly;

You don't have to be a chemist. you just need to be able to read a recipe book. All glazes are based on 100%. Usually grams.

By adding clay to prevent running, you are adding alumina because clay is a combination of alumina and silica. you would add kaolin in 3% increments, if you knew what the recipe was. The reason you choose kaolin and not any other clay is because the iron is reduced, and you won't affect the colour.

Tom.

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Chilly;

You don't have to be a chemist. you just need to be able to read a recipe book. All glazes are based on 100%. Usually grams.

By adding clay to prevent running, you are adding alumina because clay is a combination of alumina and silica. you would add kaolin in 3% increments, if you knew what the recipe was. The reason you choose kaolin and not any other clay is because the iron is reduced, and you won't affect the colour.

Tom.

Thanks Tom for your kind words and encouragement.  As others have said it's a bit daunting when you feel you are the only person in your universe who is interested in making your own glazes.  It's fantastic to have the support of the folks on this forum.  Now all I need is "forum or virtual" firing so I can test every day instead of every 3 months!

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