Paul on wed 22 sep 04
Hello,=20
I am looking for advice on how to go about single-firing platters.
Trying to bisque so many platters (about 14" diameter) in my old
electric kiln is slowing down the production system and I rarely bisque
in my gas kiln. In this case, the platters are all sprayed with a single
ash glaze which has already been known to work well in single fire
applications.
the reason I ask this question is because I tried doing this about two
years ago, and got a large percentage of cracks - in some cases, they
cracked just after the glaze dried, and in others they cracked in the
kiln. My theory is that the glaze I was spraying with had too much water
in it and I applied too much - in some cases it seemed to puddle on the
surface of the platter since the glaze did not absorb as quickly as in
bisque. Since then, I have sprayed thousands of pots (on bisque) and am
better at it, mainly because I keep glazes for spraying very thick in
the bucket, with just enough water content to allow them to move through
the spray nozzle. Plus I add veegum and sometimes bentonite. So I am
thinking if I apply this technique to single fire, it will work better
next time around. But I would really like to hear from anyone who single
fires, especially platters, and if there is any advice on how to keep
them from cracking. Thanks,
Paul B
Falmouth, KY
Paul Herman on wed 22 sep 04
Hi Paul,
You have to dampen both sides of the piece. Spray the glaze on, then
spritz some water on the back (bottom) of the platter. This will
equalise the clay's expansion. Tuscarora Pottery school technique, used
by Dennis Parks.
good glazing,
Paul Herman
Great Basin Pottery
Doyle, California US
http://www.greatbasinpottery.com/
----------
>From: Paul
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: SINGLE-FIRING PLATTERS
>Date: Wed, Sep 22, 2004, 8:05 AM
>
> the reason I ask this question is because I tried doing this about two
> years ago, and got a large percentage of cracks - in some cases, they
> cracked just after the glaze dried, and in others they cracked in the
> kiln. My theory is that the glaze I was spraying with had too much water
> in it and I applied too much - in some cases it seemed to puddle on the
> surface of the platter since the glaze did not absorb as quickly as in
> bisque. Since then, I have sprayed thousands of pots (on bisque) and am
> better at it, mainly because I keep glazes for spraying very thick in
> the bucket, with just enough water content to allow them to move through
> the spray nozzle. Plus I add veegum and sometimes bentonite. So I am
> thinking if I apply this technique to single fire, it will work better
> next time around. But I would really like to hear from anyone who single
> fires, especially platters, and if there is any advice on how to keep
> them from cracking. Thanks,
>
> Paul B
Tony Ferguson on wed 22 sep 04
Paul,
Handle them carefully. Adding some fiber to the clay for platters really
increases their green strength as well.
--don't puddle the glaze
--apply one side, let it dry, then the other.
--porcelain single fires very well because its particles are tighter--but do
not oversaturate.
--take care to dry the work slowly. Fast drying creates more stress.
I glaze work nearly as I would any bisque--just have to be gentle.
Spraying will give you the highest % of success rate.
It comes down very much to your claybody. Test that I have done--I have
glazed a number of the same forms with different claybodies and some were
fine while others ripped apart, split, cracked, pulled, etc. Claybody very
important, but learn to adapt your glazing technique to anything.
Tony Ferguson
fergyart@yahoo.com
----- Original Message -----
From: "Paul"
To:
Sent: Wednesday, September 22, 2004 10:05 AM
Subject: SINGLE-FIRING PLATTERS
Hello,
I am looking for advice on how to go about single-firing platters.
Trying to bisque so many platters (about 14" diameter) in my old
electric kiln is slowing down the production system and I rarely bisque
in my gas kiln. In this case, the platters are all sprayed with a single
ash glaze which has already been known to work well in single fire
applications.
the reason I ask this question is because I tried doing this about two
years ago, and got a large percentage of cracks - in some cases, they
cracked just after the glaze dried, and in others they cracked in the
kiln. My theory is that the glaze I was spraying with had too much water
in it and I applied too much - in some cases it seemed to puddle on the
surface of the platter since the glaze did not absorb as quickly as in
bisque. Since then, I have sprayed thousands of pots (on bisque) and am
better at it, mainly because I keep glazes for spraying very thick in
the bucket, with just enough water content to allow them to move through
the spray nozzle. Plus I add veegum and sometimes bentonite. So I am
thinking if I apply this technique to single fire, it will work better
next time around. But I would really like to hear from anyone who single
fires, especially platters, and if there is any advice on how to keep
them from cracking. Thanks,
Paul B
Falmouth, KY
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Hank Murrow on wed 22 sep 04
On Sep 22, 2004, at 8:05 AM, Paul wrote:
>
> I am looking for advice on how to go about single-firing platters.
> Trying to bisque so many platters (about 14" diameter) in my old
> electric kiln is slowing down the production system and I rarely bisque
> in my gas kiln. In this case, the platters are all sprayed with a
> single
> ash glaze which has already been known to work well in single fire
> applications.
Dear Paul;
Have you tried bisquing your platters on edge in your electric? I
bisque all my platters and plates on edge up to 20" diameter, filling
the ten-sided kiln very effectively. I never get cracks and nothing
will warp unless it goes in still damp. If more efficient packing would
allow you to bisque, more glaze choices would be open to you.
Cheers, Hank in Eugene
murrow.biz/hank
Roger Strom on wed 22 sep 04
Hi Hank,
Your advice caught my attention. How do you set them up on edge?
What do they rest against? Do you leave space between them?
Thanks,
Roger in Phoenix
On Wednesday, September 22, 2004, at 10:20 AM, Hank Murrow wrote:
> On Sep 22, 2004, at 8:05 AM, Paul wrote:
>>
>> I am looking for advice on how to go about single-firing platters.
>> Trying to bisque so many platters (about 14" diameter) in my old
>> electric kiln is slowing down the production system and I rarely
>> bisque
>> in my gas kiln. In this case, the platters are all sprayed with a
>> single
>> ash glaze which has already been known to work well in single fire
>> applications.
>
> Dear Paul;
>
> Have you tried bisquing your platters on edge in your electric? I
> bisque all my platters and plates on edge up to 20" diameter, filling
> the ten-sided kiln very effectively. I never get cracks and nothing
> will warp unless it goes in still damp. If more efficient packing would
> allow you to bisque, more glaze choices would be open to you.
>
> Cheers, Hank in Eugene
> murrow.biz/hank
>
> _______________________________________________________________________
> _______
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Hank Murrow on wed 22 sep 04
On Sep 22, 2004, at 11:41 AM, Roger Strom wrote:
> Hi Hank,
> Your advice caught my attention. How do you set them up on edge?
> What do they rest against? Do you leave space between them?
Dear Roger;
I lean them against the wall of the kiln, then lean the next one
tightly to the first, etc. until they reach the middle of the kiln.
Ditto from other side. then I fill the remaining space leaning them
against the middle pile. I get around thirty 10" plates per layer that
way in an eight-sided electric(23"). No cracks, not ever(unless you
fire too fast). I do my big(18"+) platters that way. Most importantly,
they must be absolutely dry if stacked on their rims, or warpage may
result.
Bowls I stack horizontally inside each other with a small piece of
advancer shelf (from broken ones) between so that they do not rest on
each other's rims. They can go a dozen high that way.
Cheers, Hank
murrow.biz/hank
murrow.biz/hank
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