Craig Martell on thu 11 sep 03
Hi:
I don't remember all the details of the initial discussion, so I may be
asking a ? that's already been answered. What is your bisque temperature?
Craig Martell Hopewell, Oregon
Ron Roy on thu 11 sep 03
Hi Kathi,
Sounds like that Armadillo clay is over fired at your temperature - what do
they say about this?
You might mention that I can fix it for them.
RR
>Over the past few weeks I have tried the suggestion given here to
>address pitting on certain forms by one glaze. I have altered my glaze
>application, I've put brush work on green pots before bisquing, I tried
>Lilli suggestion to glaze only the outside and see the result, increased
>soak on glaze firings, increased length of bisques at suggested
>temperature points.
>
>I've fired all of these tests in the same location of the kiln. I got
>pitting in every case except one--using a different clay from a Michigan
>supplier (my clay comes from Armadillo in Texas). I've done enough
>firings at this point the accept that if I want to use this glaze on
>these forms I will have to use the Michigan clay. And, while I hate
>using two clays in my studio I hate more giving up these forms with this
>glaze. And I would never consider giving up the clay from Texas. It
>works with everything else, is a pleasure to throw with, and has a
>wonderful color in unglaze work.
>
>Kathi
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Kathi LeSueur on thu 11 sep 03
Over the past few weeks I have tried the suggestion given here to
address pitting on certain forms by one glaze. I have altered my glaze
application, I've put brush work on green pots before bisquing, I tried
Lilli suggestion to glaze only the outside and see the result, increased
soak on glaze firings, increased length of bisques at suggested
temperature points.
I've fired all of these tests in the same location of the kiln. I got
pitting in every case except one--using a different clay from a Michigan
supplier (my clay comes from Armadillo in Texas). I've done enough
firings at this point the accept that if I want to use this glaze on
these forms I will have to use the Michigan clay. And, while I hate
using two clays in my studio I hate more giving up these forms with this
glaze. And I would never consider giving up the clay from Texas. It
works with everything else, is a pleasure to throw with, and has a
wonderful color in unglaze work.
Kathi
Kathi LeSueur on fri 12 sep 03
ashglaze@WVI.COM wrote:
> Hi:
>
> I don't remember all the details of the initial discussion, so I may be
> asking a ? that's already been answered. What is your bisque temperature?
>
> Craig Martell Hopewell, Oregon>>
>
>
I bisque to cone o5.
Kathi
Kathi LeSueur on fri 12 sep 03
ronroy@TOTAL.NET wrote:
>Hi Kathi,
>
>Sounds like that Armadillo clay is over fired at your temperature - what do
>they say about this?
>
>You might mention that I can fix it for them.
>
>RR
>
>
>
>>Interesting that I talked to Craig just yesterday about his clay. In my last firing I had 9 down and 10 tipping. Still had the problem. He is experimenting with altering the clay formula, replacing OM4 with C&C Ball and the fireclay with Hawthorn. He's FedExing me a sample so that I can try it before I order my next load of 5000#. I doubt if I'm overfiring the clay since this is the only glaze that has ever had problems. I also make lots of serving pieces that go in the oven and my customers never report a problem. So, I'll try the sample and keep you posted.
>>
>>
>>Kathi
>>
Dewitt on fri 12 sep 03
At 11:58 PM 9/11/2003, you wrote:
>Hi Kathi,
>
>Sounds like that Armadillo clay is over fired at your temperature - what do
>they say about this?
>
>You might mention that I can fix it for them.
>
>RR
The mid-range Armadillo clays, Cinco Blanco, Buffalo Wallow, and Cinco
Rojo, are described as Cone 5 clays in the somewhat old catalog I
have. About a year ago someone on the list mentioned she had a problem
with them slumping. I haven't seen that problem, but Waxwing Brown on
Cinco Blanco blistered and definitely looked over fired.
deg
Kathi LeSueur on sun 14 sep 03
Taylor_Hendrix@BAYLOR.EDU wrote:
>Kathi,
>
>Are these 'Dillow's cone 5 clay bodies you are talking
>about?
>
No, Balcones, Balcones White, and Dillo white are cone 10 clays. I fire
to cone 10. They are not overfired. Cone 10 is not flat and 11 has not
moved.
Kathi
Craig Martell on sun 14 sep 03
Kathi sez:
>I bisque to cone o5.
Hello Kathi:
I was thinking that if the blisters were not caused by an overfire, maybe
the offending clay has more organics than the other clay that's not
experiencing the problem. Maybe a hotter bisque fire would help. You
might try cone 04.
I just read your last post about the 'dillo guy working on the claybody and
making some changes. If this works, there would, of course, be no reason
to change your bisque temp.
regards, Craig Martell Hopewell, Oregon
Kathi LeSueur on sun 14 sep 03
ashglaze@WVI.COM wrote:
> Kathi sez:
>
>> I bisque to cone o5.
>
>
> Hello Kathi:
>
> I was thinking that if the blisters were not caused by an overfire, maybe
> the offending clay has more organics than the other clay that's not
> experiencing the problem. Maybe a hotter bisque fire would help. You
> might try cone 04.
>
> I just read your last post about the 'dillo guy working on the
> claybody and
> making some changes. If this works, there would, of course, be no reason
> to change your bisque temp.>>
>
>
> Thanks for your input Craig. As I've said before, this only happens
> with one glaze on certain forms. Vases, utensil holders. The glaze is
> opacified by titanium. Have had it on other forms but adjustments to
> firing in both bisque and glaze seem to have taken care of it. But,
> never, ever with my other glazes. Hopefully, the changes being made to
> the clay body will take care of the problem. I really don't want to
> use two clays but will if I have too. This glaze is too good a seller.
Kathi
>
Hendrix, Taylor J on sun 14 sep 03
Kathi,
Are these 'Dillow's cone 5 clay bodies you are talking
about? Which ones exactly? I have been using their
cone 5 bodies Cinco Blanco, Cinco Rojo, and Buffalo Wallow
almost exclusively since I started learning potting. I do=20
indeed love the way they both throw, but not too long ago
we were having trouble with the rojo. Dillo told us it=20
was because we were pushing it to cone 6, which indeed my
teacher and I were doing. She has fired it to cone 6 for
years. It hasn't been a problem lately. Go figure.
Pushing the clay like we do does entail certain risks that
we must accept if we are not willing to make up our own
bodies. Teacher has no desire to do so. I, on the other
hand, can't wait till I can start formulating my own clay
bodies and have complete (har har) control of things.
Taylor, in Waco
-----Original Message-----
From: Ron Roy [mailto:ronroy@TOTAL.NET]=20
Sent: Thursday, September 11, 2003 11:58 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: glaze mystery update
Hi Kathi,
Sounds like that Armadillo clay is over fired at your temperature ...
Ron Roy on mon 15 sep 03
Hi Kathi,
The changes Craig is going to do will not stop the clay from overfiring by
the way - if that is the problem.
It occurred to me that I should explain the difference between clay over
firings because of reduced iron and that which is melting too much because
it is over fluxed. It is the same problem.
If the iron in the body is reduced because of bisquing too fast and/or
because there is not enough oxygen present the reduced iron turns into a
flux. In a body that just has too much flux to start with - the result is
the same. An overfired body that begins to produce gas - which, when
escaping, bubbles through the glaze and causing blistering and/or pin
holes. We can tell if that is the problem because - when it's refired the
problem gets worse.
It also occurs to me - if this is a dark body - perhaps we should look at
the bisquing - are the bubbles in any sort of pattern - more where the clay
is thicker?
You can actually see the gas bubbles in the clay when you break it open -
sometimes with just your eyes but us older folks probably need a magnifying
glass.
Carbon monoxide is the stuff that is dangerous in two ways - it can poison
you - and reduce the iron in your clay to make it over flux.
I don't know if I have under explained all this - if so just ask.
RR
>>Sounds like that Armadillo clay is over fired at your temperature - what do
>>they say about this?
>>
>>You might mention that I can fix it for them.
>>
>>RR
>>
>>
>>
>>>Interesting that I talked to Craig just yesterday about his clay. In my
>>>last firing I had 9 down and 10 tipping. Still had the problem. He is
>>>experimenting with altering the clay formula, replacing OM4 with C&C
>>>Ball and the fireclay with Hawthorn. He's FedExing me a sample so that I
>>>can try it before I order my next load of 5000#. I doubt if I'm
>>>overfiring the clay since this is the only glaze that has ever had
>>>problems. I also make lots of serving pieces that go in the oven and my
>>>customers never report a problem. So, I'll try the sample and keep you
>>>posted.
Kathi
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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