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^6 oxidation question

updated sun 11 nov 01

 

Gretchen Zinkan on fri 9 nov 01


Hello everyone and thank you for all your postings...I have learned so much
from you all. I have been lurking for a couple of months now...and have
found answers to questions I didn't know I had.

I fired a dish with some of the recipes discussed here...Oxblood, Temoku
Gold and a recipe I'd used for a long time...a Strini with RIO. I was so
excited...(read: impatient) to open the kiln...I took this particular pot
out when it was still pretty hot...and the results were totally amazing. As
it hit the colder air..I could see the glaze patterns changing creating
lines (like whispy clouds). When I grabbed the pot with my leather
gloves...those places I touched also changed (musta been the smoke ehe??)

Could some of you wise potters tell me what was happening? I would like to
be able to re-create this situation with some other pieces.

Question 2

Will all my ^6 glazes also work on ^6 porcelain? Anything I need to be
aware of?

Thanks to you all

Gretchen Zinkan
British Columbia

Paul Lewing on fri 9 nov 01


> on 11/9/01 9:22 AM, Gretchen Zinkan at gzinkan@CYBERLINK.BC.CA wrote:
>
>> Question 2
>>
>> Will all my ^6 glazes also work on ^6 porcelain? Anything I need to be
>> aware of?

Gretchen,
John Hesselberth has already given you some good information on how the fit
of your glazes might change when you change clay bodies.
But to judge whether a glaze will work on another body, you might need to
ask what you mean by "work". Changing from a dark body to a white body may
give you a completely different color than you're used to, especially if the
glaze is at all transparent. Chances are that glossy glazes on a dark body
will still be glossy on porcelain, and matte glazes will be matte, but if
your favorite chocolate brown glaze comes out amber colored, you might not
think it "worked".
It's like asking if your oxidation glazes will "work" in reduction at the
same temperature. Well, they'll probably melt and fit about the same (with
a few exceptions), but they could well look completely different. You might
not like them as well, you might like them better, but did they "work"?
Paul Lewing, Seattle

Ababi on fri 9 nov 01


Dear potter.
I open the kiln when it is at 220C 428F a little bit. Open the door at
200C 392F. Delicate glazes like the one you write about I leave in the
kiln down to 150 100C 212F.
Every glaze you make test on every claybody you might use.
Hope it helps
Ababi
In the land of milk and Honey

Cindy Strnad on fri 9 nov 01


Dear Grechen,

How hot is "pretty hot"? Pots do change in
appearance as they cool. I have seen this effect
you describe, too, and I think it's just a result
of watching the pot cool quickly. Some forms,
glazes, and bodies can take this kind of
treatment, and others will be damaged. I've seen
large bowls crack clean in half because someone
(me) got in a hurry. So have fun, but be aware.

Best wishes,

Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
cindy@earthen-vessels-pottery.com
http://www.earthen-vessels-pottery.com

John Hesselberth on fri 9 nov 01


on 11/9/01 9:22 AM, Gretchen Zinkan at gzinkan@CYBERLINK.BC.CA wrote:

> Question 2
>
> Will all my ^6 glazes also work on ^6 porcelain? Anything I need to be
> aware of?

Hi Gretchen,

Maybe, maybe not. There are at least two things you should watch out for.
One is clay/glaze fit. Your porcelain may have different thermal
expansion/contraction characteristics than your stoneware. One may craze or
shiver where the other does not. The second thing is that porcelain almost
always has more fluxing materials in the clay body itself. These can
interact with he glaze and cause a glaze that almost runs on stoneware to
run right off the pot on porcelain. Actually every glaze needs to be
checked on every different clay body you use. They all have slightly
different characteristics and can interact with the clay differently.

Regards,

John

Web site: http://www.frogpondpottery.com Email: john@frogpondpottery.com

"The life so short, the craft so long to learn." Chaucer's translation of
Hippocrates, 5th cent. B.C.