Renate I. Shiver on sun 7 nov 99
Is anyone aware of any impacts to firing at a high altitude? I fire in an
electric kiln at around 7,000 feet. Prior to relocating here, about a year
ago, had very few problems with my glaze firings. I am now experiencing
blistering, sometimes very severe. Have tried to eliminate the problem
following conventional wisdom ie: slower firing, soak, etc. I have even
fired at a cone lower which seems to help. The blistering occurs when
firing different glazes so it is not just one glaze.
Have also thought that maybe our hard water may be the reason and used
distilled water to mix one of my glazes, but to no avail ... still
experienced the blistering. I am sure there is something I am missing. Any
help would be greatly appreciated!
Renate
Ruidoso, NM
Jonathan Kaplan on mon 8 nov 99
We routinely fire our 50 cuft gas car kiln at Steamboat Springs
altitiude....about 6000 feet up. We have never had a problem. We have a
forced air system and use an oxygen probe.
Jonathan
Jonathan Kaplan
Ceramic Design Group
PO Box 775112
Steamboat Springs CO 80477
voice and fax 970 879-9139
jonathan@csn,net
http://www.sni.net/ceramicdesigin
Dave Finkelnburg on tue 9 nov 99
Renate,
I am having blistering problems in electric also. Are you using
Gerstley Borate in any recipes? I'm wondering if the material has changed?
It's really frustrating. I don't see why elevation should have an effect on
what you do. I didn't have any problems here at 4,500 feet until the last
few months.
Dave Finkelnburg
Idaho Fire Pottery
dfinkeln@cyberhighway.net
-----Original Message-----
From: Renate I. Shiver
To: CLAYART@LSV.UKY.EDU
Date: Sunday, November 07, 1999 3:33 PM
Subject: Impacts of High Altitude on Firing?
>----------------------------Original message----------------------------
>Is anyone aware of any impacts to firing at a high altitude? I fire in an
>electric kiln at around 7,000 feet. Prior to relocating here, about a year
>ago, had very few problems with my glaze firings. I am now experiencing
>blistering, sometimes very severe. Have tried to eliminate the problem
>following conventional wisdom ie: slower firing, soak, etc. I have even
>fired at a cone lower which seems to help. The blistering occurs when
>firing different glazes so it is not just one glaze.
>
>Have also thought that maybe our hard water may be the reason and used
>distilled water to mix one of my glazes, but to no avail ... still
>experienced the blistering. I am sure there is something I am missing.
Any
>help would be greatly appreciated!
>
>Renate
>Ruidoso, NM
>
Renate I. Shiver on wed 10 nov 99
David,
Yes, I do use Gerstley Borate in some of my recipes, but not all and not in
the glazes where I am experiencing the worst blistering. In fact, if I have
any problems with glazes using significant amounts of this material it is
crawling. I solved that problem by reading an article in Pottery Making
Illustrated, Spring 1999, Volume 2, Number 2, page36 by Michael Hamlin. It
seems as if Gerstley Borate is a common culprit when it comes to crawling.
Of course, that doesn't answer your questions about the blistering. Here's
what I've discovered...
I think I have found an important lead about my particular blistering
problem by reading the archives on the subject at the Clayart Discussions by
Subject web site ( http://www.potters.org/categories.htm ). This is a great
site for research. The blistering information was found in the glazes
category, faults subcategory. At any rate, I believe my problem is that I
might be bisque firing in a slight reduction atmosphere which changes the
chemical composition of the iron in my clay which in turn creates problems
with gases being released from the clay body during a glaze firing. The
reason I believe this may be a key lead for me is that when I refire to heal
the blistering it only gets worse. I have no idea how or whether a
reduction atmosphere is being created in my electric kiln during bisque
firing but you can be sure I am going to eliminate that as a probable cause.
I don't know whether this addresses your specific problem, but you may want
to research the archives on blistering on the web site mentioned above. I
doubt it is the cause for your blistering. There may be more experienced
people on this list that can confirm or correct my understanding about
Gerstley Borate, but I doubt it is the cause for your blistering.
I wish you success in finding your solution to eliminating blistering ... it
is a killer of ware.
Renate
Ruidoso, NM
-----Original Message-----
From: Dave Finkelnburg
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, November 09, 1999 11:57 AM
Subject: Re: Impacts of High Altitude on Firing?
>----------------------------Original message----------------------------
>Renate,
> I am having blistering problems in electric also. Are you using
>Gerstley Borate in any recipes? I'm wondering if the material has
changed?
>It's really frustrating. I don't see why elevation should have an effect
on
>what you do. I didn't have any problems here at 4,500 feet until the last
>few months.
> Dave Finkelnburg
> Idaho Fire Pottery
> dfinkeln@cyberhighway.net
>
>-----Original Message-----
>From: Renate I. Shiver
>To: CLAYART@LSV.UKY.EDU
>Date: Sunday, November 07, 1999 3:33 PM
>Subject: Impacts of High Altitude on Firing?
>
>
>>----------------------------Original message----------------------------
>>Is anyone aware of any impacts to firing at a high altitude? I fire in an
>>electric kiln at around 7,000 feet. Prior to relocating here, about a
year
>>ago, had very few problems with my glaze firings. I am now experiencing
>>blistering, sometimes very severe. Have tried to eliminate the problem
>>following conventional wisdom ie: slower firing, soak, etc. I have even
>>fired at a cone lower which seems to help. The blistering occurs when
>>firing different glazes so it is not just one glaze.
>>
>>Have also thought that maybe our hard water may be the reason and used
>>distilled water to mix one of my glazes, but to no avail ... still
>>experienced the blistering. I am sure there is something I am missing.
>Any
>>help would be greatly appreciated!
>>
>>Renate
>>Ruidoso, NM
>>
>
Reg Wearley on wed 10 nov 99
Hi Dave-
Altitude does have an effect on any material that
is exposed to the atmosphere and brought up to (or
very near) its boiling point. Vaporization rapidly
takes place at that point and the more volitile the
material the more 'intense' the vaporization (ie.
the tendency to form bubbles). However, I cannot
visulize our glazes reaching the boiling temp. At
the same time they do become liquid (mostly like
syrup) and since a number of chemical changes take
place, some of which form & expel gases, virtually
the same principle applies. Therefore, the higher
the atmospheric pressure(lower altitude) against the
melted material, the harder it is for the bubbles to
form and start to escape. I would guess that is where
the idea of 'soaking' comes in-to allow the bubbles
time to break through the surface and the surface
has time to heal. Make sense?
Think about what goes on inside your mothers pressure
cooker-since the pressure is greatly increased, the
boiling point of the water is proportionally
increased. Let me know what you think. -Reg
--- Dave Finkelnburg
wrote:
> ----------------------------Original
> message----------------------------
> Renate,
> I am having blistering problems in electric
> also. Are you using
> Gerstley Borate in any recipes? I'm wondering if
> the material has changed?
> It's really frustrating. I don't see why elevation
> should have an effect on
> what you do. I didn't have any problems here at
> 4,500 feet until the last
> few months.
> Dave Finkelnburg
> Idaho Fire Pottery
> dfinkeln@cyberhighway.net
>
> -----Original Message-----
> From: Renate I. Shiver
> To: CLAYART@LSV.UKY.EDU
> Date: Sunday, November 07, 1999 3:33 PM
> Subject: Impacts of High Altitude on Firing?
>
>
> >----------------------------Original
> message----------------------------
> >Is anyone aware of any impacts to firing at a high
> altitude? I fire in an
> >electric kiln at around 7,000 feet. Prior to
> relocating here, about a year
> >ago, had very few problems with my glaze firings.
> I am now experiencing
> >blistering, sometimes very severe. Have tried to
> eliminate the problem
> >following conventional wisdom ie: slower firing,
> soak, etc. I have even
> >fired at a cone lower which seems to help. The
> blistering occurs when
> >firing different glazes so it is not just one
> glaze.
> >
> >Have also thought that maybe our hard water may be
> the reason and used
> >distilled water to mix one of my glazes, but to no
> avail ... still
> >experienced the blistering. I am sure there is
> something I am missing.
> Any
> >help would be greatly appreciated!
> >
> >Renate
> >Ruidoso, NM
> >
>
=====
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Ray Aldridge on thu 11 nov 99
At 12:10 PM 11/10/99 EST, you wrote:
>----------------------------Original message----------------------------
>David,
>
>Yes, I do use Gerstley Borate in some of my recipes, but not all and not in
>the glazes where I am experiencing the worst blistering.
Have you tried firing your bisque a little hotter, by a cone or two? I
think that's what I'd try next.
Ray
Aldridge Porcelain and Stoneware
http://www.goodpots.com
Jeff Lawrence on thu 11 nov 99
Hello Renate in Ruidoso,
I always used to bisque fire fast, for reliably flawed surfaces. If your
elements don't match your wall voltage, the kiln will fire fast and you'll
have the same problem.
Jeff
Renate I. Shiver on fri 12 nov 99
Jeff,
Thanks for the information. I fire my bisque slowly to cone 04 using a
11-12 program, but I have no idea whether my elements match my wall voltage.
I assume that since a qualified electrician installed the wiring, outlet,
circuit, etc. specifically for my kiln that he would have made sure that the
voltage coming in was okay. Of course we do experience surges and brown
outs at times. How do I test this or eliminate it as a possible problem?
Renate
Ruidoso, NM
-----Original Message-----
From: Jeff Lawrence
To: CLAYART@LSV.UKY.EDU
Date: Thursday, November 11, 1999 4:08 PM
Subject: Re: Impacts of High Altitude on Firing?
----------------------------Original message----------------------------
Hello Renate in Ruidoso,
I always used to bisque fire fast, for reliably flawed surfaces. If your
elements don't match your wall voltage, the kiln will fire fast and you'll
have the same problem.
Jeff
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