tonya Johnson on thu 22 nov 07
Hello,
I have been using a turquoise glaze called Coleman's Turquoise for about 3
years now. I put it on the design part of the pot and a yellow glaze on the
rest. It is a cone 9/10 glaze that I fire in a propane gas reduction kiln. 4 or
5 firings ago, I noticed that a few pots had begun to blistered a little.
Then I had a load with a few more. Next, I had a few more and then the next
load about half blistered. Along the way, I remixed the glaze (twice) and the
next load EVERYTHING blistered. I had my gas regulator replaced and only fired
a few turquoise pieces. They are also blistered. Nothing else blisters,
although this last firing I did get a few blisters or really bubbles in a
different copper matt glaze I use. I don't know what else to do? For nearly three
years the glaze came out a consistant blue/green matt turquoise. After the load
where everything blistered, I was ready to go get an applications for
McDonald's. Instead I dried my tears, went out and bought a box of ice cream, and
watched two movies in a row (unheard of in November). The next day, I smeared a
cone 6 turquoise glaze, thick from the side of the bucket, onto the
blistered turquoise area of a few of the pots and refired in the electric kiln to
cone 6. The blisters smoothed out and I saved the pots. In fact they look great
and I'm gonna sell em! In the mean time I still have the problem. Below I
will include this recipe. Any ideas?
Thanks in advance : ) Tonya in Louisville, KY
Bar. Carb. 22.83
whit 9.78
custer 56.52
om4 10.87
zinc ox 5.98
copper carb 4.24
rutile 4.24
bento 2.0
ps. Happy Thanksgiving!
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Donna Kat on fri 23 nov 07
1) are any of your ingredients new?
2) are you using cones to check that you have gotten the heat work you
want.
3) mix up 500 grams of the glaze again just to be sure that you haven't
messed up (it can happen).
On Thu, 22 Nov 2007 17:27:15 EST, tonya Johnson wrote:
>Hello,
>I have been using a turquoise glaze called Coleman's Turquoise for about
3
>years now. I put it on the design part of the pot and a yellow glaze on
the
>rest. It is a cone 9/10 glaze that I fire in a propane gas reduction
kiln. 4 or
>5 firings ago, I noticed that a few pots had begun to blistered a little.
>Then I had a load with a few more. Next, I had a few more and then the
next
>load about half blistered. Along the way, I remixed the glaze (twice)
and the
>next load EVERYTHING blistered. I had my gas regulator replaced and only
fired
>a few turquoise pieces. They are also blistered. Nothing else blisters,
>although this last firing I did get a few blisters or really bubbles in a
>different copper matt glaze I use. I don't know what else to do? For
nearly three
>years the glaze came out a consistant blue/green matt turquoise. After
the load
>where everything blistered, I was ready to go get an applications for
>McDonald's. Instead I dried my tears, went out and bought a box of ice
cream, and
>watched two movies in a row (unheard of in November). The next day, I
smeared a
>cone 6 turquoise glaze, thick from the side of the bucket, onto the
>blistered turquoise area of a few of the pots and refired in the
electric kiln to
>cone 6. The blisters smoothed out and I saved the pots. In fact they
look great
>and I'm gonna sell em! In the mean time I still have the problem. Below I
>will include this recipe. Any ideas?
>Thanks in advance : ) Tonya in Louisville, KY
>
>
>Bar. Carb. 22.83
>whit 9.78
>custer 56.52
>om4 10.87
>zinc ox 5.98
>copper carb 4.24
>rutile 4.24
>bento 2.0
>
>ps. Happy Thanksgiving!
>
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
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KATHI LESUEUR on fri 23 nov 07
On Nov 22, 2007, at 5:27 PM, tonya Johnson wrote:
> Hello,
> I have been using a turquoise glaze called Coleman's Turquoise for
> about 3
> years now. I put it on the design part of the pot and a yellow
> glaze on the
> rest. It is a cone 9/10 glaze that I fire in a propane gas
> reduction kiln. 4 or
> 5 firings ago, I noticed that a few pots had begun to blistered a
> little.
> Then I had a load with a few more. Next, I had a few more and then
> the next
> load about half blistered. .......
>
>
> Bar. Carb. 22.83
> whit 9.78
> custer 56.52
> om4 10.87
> zinc ox 5.98
> copper carb 4.24
> rutile 4.24
> bento 2.0
>
> ps. Happy Thanksgiving!
>
>
>
I would bet that the problem is with the rutile. It seems many people
are having problems with glazes containing this material. I've had
good sucess by calcining the rutile in a bowl with my bisque firings.
It clumps a little but is easily ground back to a powder with mortor
and pestle.
Kathi
Ron Roy on sat 24 nov 07
Hi Tonya,
Just as an aside - your glaze is way short of silica - which means - if you
use it as a liner it will leach barium into foods - and it will be crazed
which exposes more of the glaze surface to any acidic food.
Zinc oxide is easily reduced to the metal - which boils at quite a low
temperature - most cone 10 glazes don't need it because it's usually gone
before it can work. It may be the cause of the blistering. Try the glaze
without it - if it still needs more flux let me know and I'll adjust it for
you.
Actually without the zinc it's a lot better glaze with enough silica to be
a good liner - if there was not so much barium. Don't let the cats drink
the glaze water!
RR
>Hello,
>I have been using a turquoise glaze called Coleman's Turquoise for about 3
>years now. I put it on the design part of the pot and a yellow glaze on the
>rest. It is a cone 9/10 glaze that I fire in a propane gas reduction
>kiln. 4 or
>5 firings ago, I noticed that a few pots had begun to blistered a little.
>Then I had a load with a few more. Next, I had a few more and then the next
>load about half blistered. Along the way, I remixed the glaze (twice) and the
>next load EVERYTHING blistered. I had my gas regulator replaced and only fired
>a few turquoise pieces. They are also blistered. Nothing else blisters,
>although this last firing I did get a few blisters or really bubbles in a
>different copper matt glaze I use. I don't know what else to do? For
>nearly three
>years the glaze came out a consistant blue/green matt turquoise. After
>the load
>where everything blistered, I was ready to go get an applications for
>McDonald's. Instead I dried my tears, went out and bought a box of ice
>cream, and
>watched two movies in a row (unheard of in November). The next day, I
>smeared a
>cone 6 turquoise glaze, thick from the side of the bucket, onto the
>blistered turquoise area of a few of the pots and refired in the electric
>kiln to
>cone 6. The blisters smoothed out and I saved the pots. In fact they look
>great
>and I'm gonna sell em! In the mean time I still have the problem. Below I
>will include this recipe. Any ideas?
>Thanks in advance : ) Tonya in Louisville, KY
>
>
>Bar. Carb. 22.83
>whit 9.78
>custer 56.52
>om4 10.87
>zinc ox 5.98
>copper carb 4.24
>rutile 4.24
>bento 2.0
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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