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glaze defects - blistering, causes of....

updated wed 30 apr 97

 

Talbott on wed 2 apr 97

If you have a list of causes for blisters in glazes, I would appreciate
hearing from you... Marshall

1ST ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summmer 1997)
http://fmc.utm.edu/~dmcbeth/cag/naples.htm

Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
WBS Live Chat Room, Sat Nites 10 PM EST, Private Room: Clayarters

M Richens on mon 7 apr 97

In article , Talbott
writes
>----------------------------Original message----------------------------
>If you have a list of causes for blisters in glazes, I would appreciate
>hearing from you... Marshall
>
> 1ST ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summmer 1997)
> http://fmc.utm.edu/~dmcbeth/cag/naples.htm
>
> Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
> Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
> WBS Live Chat Room, Sat Nites 10 PM EST, Private Room: Clayarters

One possible is that you have a very soft glass component which is
sealing the body too quickly. Either harden up the glaze or slow down
the initial heat rate to allow any gases to escape.
HTH
Max
--
Max Richens max@richens.demon.co.uk +44 (0) 1925756241
Enamel Consultant - Ceramist - Analyst programmer
Software for Batch Formulation and Millroom control.

Don Walton on tue 8 apr 97

At 12:18 PM 4/7/97 EDT, you wrote:
>----------------------------Original message----------------------------
>In article , Talbott
> writes
>>----------------------------Original message----------------------------
>>If you have a list of causes for blisters in glazes, I would appreciate
>>hearing from you... Marshall



What kind of glazes are you using , reduction or oxidation? Also, what clay
body and cone?

Don Walton

Talbott on thu 10 apr 97

Thanks for the responses so far... we fire cone 9/10 reduction in a
gas kiln and the claybody is stoneware... I think I fired too fast during
the glaze fire and a little too hot as well ^10/^11... and I also think I
overfired the bisque... Usually bisque to ^06 and I went to ^04/^03... Got
to be MORE careful and less distracted during the firings....

Marshall (thinking.... this southern boy has really got to get his act
together!!!)

>If you have a list of causes for blisters in glazes, I would appreciate
>hearing >from you... Marshall

1ST ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summmer 1997)
http://fmc.utm.edu/~dmcbeth/cag/naples.htm

Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
WBS Live Chat Room, Sat Nites 10 PM EST, Private Room: Clayarters

Don Walton on sat 12 apr 97

At 07:10 AM 4/10/97 EDT, you wrote:
>----------------------------Original message----------------------------
> Thanks for the responses so far... we fire cone 9/10 reduction in a
>gas kiln and the claybody is stoneware... I think I fired too fast during
>the glaze fire and a little too hot as well ^10/^11... and I also think I
>overfired the bisque... Usually bisque to ^06 and I went to ^04/^03... Got
>to be MORE careful and less distracted during the firings....
>
>Marshall (thinking.... this southern boy has really got to get his act
>together!!!)
>
>>If you have a list of causes for blisters in glazes, I would appreciate
>>hearing >from you... Marshall
>
> 1ST ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summmer 1997)
> http://fmc.utm.edu/~dmcbeth/cag/naples.htm
>
> Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
> Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
> WBS Live Chat Room, Sat Nites 10 PM EST, Private Room: Clayarters
>
>
we had a terrible time with blisters in rutile blue/ copper red type glazes
approx. 2 years ago, I narrowed it very quickly to the om4 ball calay in the
body we were using at the time(Phoenix from Highwater Clays). We sell the
work of three other potters in our gallery who were having the same problem
at the same time.
We tried everything, raising the bisque temp from 06 to 04, soaking the
bisque kiln, different glaze mix, but it all came back to the om4 clay in
the body. I knew this becase I had some old om4 that worked fine and when I
mixed a body with new om4 we got big ugly blisters. Our biggest problem was
getting the supplier to agree that there was a problem with the clay and
that it wasn't something we were doing. After a lengthy period it was
discovered that there are different grades of om4 and evidently the one we
had in our body wasn't ground fine enough. I know this sounds weird, but
that is what they told me the problem was. Anyway, for now the blisters are
gone and we are having good firings again. I know there are other causes for
blisters, but this is one we are VERY familar with. Has anyone had any
problems with B-mix lately, We are testing this now and was just wondering?

Don Walton in NC waiting for
spring again

David Donica on tue 15 apr 97

Hello Don- thanks for your thoughts on blistering. As for B-mix, I use a
lot of it (with sand) and like it as it's so white and easier to deal with
than porcelain- I've heard of people having terrible trouble with handles
popping off of things they've made but I haven't had that problem, however
I dry things really slowly and take a lot of care in attaching any handles.
I throw large plates with it and have some cookware made from it- probably
not the best choice for the latter but no problems so far.
Maggie Shepard
FireWorks Pottery
Mt. Shasta, Calif.