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Fixing a Runny Glaze


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#1 TJR

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Posted 28 April 2013 - 07:34 PM

I have been testing this glaze, and I like the surface-kind of a bright Celadon without the colourants. I want to prevent it from running as it does now. I know that I need to up the clay content, but by what percentage? How much kaolin can I add without changing the character/shininess of the glaze?
Here's the recipe
Cone 10 reduction
Synthetic Ash.
Potash feldspar 33
Whiting 33
Albany slip 13
Kaolin[EPK[ 5
Bentonite 5
Bone Ash 3.5
Dolomite 2.5
Silica[flint] 1.5
------
96.5
Red Iron ox. 3
Cobalt carb. 1.5
Total 100

#2 Mark C.

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Posted 28 April 2013 - 07:49 PM

I would add double EPK in a small test as I tend to make large jumps to see whats happinging quickly.You can make the test in stages as you add more then dip a tile then addd more EPK and dip agin and so on.
If its to much cut that to 1/2 of double.
There will be a point that it gets dry as EPK has so much silica and alumina.
Good luck testing
Mixing a few tests today for this weeks glaze fire as well.
Mark Cortright
www.liscomhillpottery.com

#3 TJR

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Posted 28 April 2013 - 08:49 PM

I would add double EPK in a small test as I tend to make large jumps to see whats happinging quickly.You can make the test in stages as you add more then dip a tile then addd more EPK and dip agin and so on.
If its to much cut that to 1/2 of double.
There will be a point that it gets dry as EPK has so much silica and alumina.
Good luck testing
Mixing a few tests today for this weeks glaze fire as well.


Mark;
I am thinking like 5%, then another 5%, then another 5% in the same cup.
Thanks for your rapid response. Sounds like you are back at it ,and the holiday is over.
Tom.

#4 Mark C.

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Posted 28 April 2013 - 09:13 PM


I would add double EPK in a small test as I tend to make large jumps to see whats happinging quickly.You can make the test in stages as you add more then dip a tile then addd more EPK and dip agin and so on.
If its to much cut that to 1/2 of double.
There will be a point that it gets dry as EPK has so much silica and alumina.
Good luck testing
Mixing a few tests today for this weeks glaze fire as well.


Mark;
I am thinking like 5%, then another 5%, then another 5% in the same cup.
Thanks for your rapid response. Sounds like you are back at it ,and the holiday is over.
Tom.



Holiday is over thats for sure-fire two kilns this weekend
Mixed glazes today-will glaze a load on Monday
Just did Arizona show and next show is in two weeks at UC Davis in middle of California near Sacramento
galleries need pots now and the list goes on-
Holiday seems like a distant memory
At least we have some Great spring weather.
I like the 5 then 5% deal as you will see right away whats going on.
Mark
Mark


Mark Cortright
www.liscomhillpottery.com

#5 Marcia Selsor

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Posted 29 April 2013 - 06:43 AM

I have stopped running of glazes with as little as 3 % but maybe I didn't have as much initial running.
Marcia

#6 neilestrick

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Posted 29 April 2013 - 10:24 AM

Just adding EPK can stiffen it up, but can also alter the surface because it changes the silica/alumina ratio. To keep the ration consistent while stiffening it up, add equal parts EPK and flint (silica). Start with 2% each, and go up in 2% increments.

Neil Estrick
Kiln Repair Tech
L&L Kilns Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com





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