Sherri Kellam on sun 6 jun 04
I wanted to find out if I am using the wrong glaze or clay? I am having a slight crazing problem. Some of my tiles have crazing while others are perfect.
I use Low Fire White clay fired to Cone 05 then paint with Duncan Concepts and glaze with Ceramichrome Overglaze and fire it to Cone 06.
This combination was suggested by my local ceramics supply store -- although when I look at the Overglaze, it states to apply it to shelf cone 04-03 bisque. So am I using the wrong combination??
Thank you for any suggestions. I know that you are the 'experts'.
Sincerely,
Sherri
angel_prints@sbcglobal.net
william schran on mon 7 jun 04
Sherri wrote:>I use Low Fire White clay fired to Cone 05 then paint
with Duncan Concepts and glaze with Ceramichrome Overglaze and fire
it to Cone 06. This combination was suggested by my local ceramics
supply store -- although when I look at the Overglaze, it states to
apply it to shelf cone 04-03 bisque. So am I using the wrong
combination??<
Perhaps you've answered your own question - why don't you do your
bisque firing at cone 04-03, then see what happens?
It will be important to use witness cones for the most accurate
firing. If you rely on a cone in the kiln sitter, who knows what cone
you may be firing to.
Bill
Jon Whitney on mon 7 jun 04
I agree. In past job experience the bisque fire was always 04. This will shrink the clay some more and give the glaze the proper fit. Also if this is a glossy glaze be sure not to get anxious and open that lid before the kiln gets to room temperature. The cooler air hitting the glaze may cause crazing.
jon
> Sherri wrote:>I use Low Fire White clay fired to Cone 05 then paint
> with Duncan Concepts and glaze with Ceramichrome Overglaze and fire
> it to Cone 06. This combination was suggested by my local ceramics
> supply store -- although when I look at the Overglaze, it states to
> apply it to shelf cone 04-03 bisque. So am I using the wrong
> combination??<
>
> Perhaps you've answered your own question - why don't you do your
> bisque firing at cone 04-03, then see what happens?
>
> It will be important to use witness cones for the most accurate
> firing. If you rely on a cone in the kiln sitter, who knows what cone
> you may be firing to.
>
> Bill
>
> ______________________________________________________________________________
> 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.
Ron Roy on wed 9 jun 04
Just to clarify - if the body is bisque fired higher than the glaze firing
- then - with some types of low fired clays - enstatite helps with crazing.
If the body is bisque fired lower than the glaze then changing the bisque
firing temperature will not help the problem - except - if the bisque
firing is raised - the glaze might be applied thinner. Thickly applied
glazes are more likely to craze faster - than thinly applied glazes.
I think some glazes - when applied thinly - may even pick up enough silica
from a clay body to actually affect the expansion and stop crazing - with
some glazes that are close to not crazing.
Not as easy to expalin as I thought it would be.
RR
>I agree. In past job experience the bisque fire was always 04. This will
>shrink the clay some more and give the glaze the proper fit. Also if this
>is a glossy glaze be sure not to get anxious and open that lid before the
>kiln gets to room temperature. The cooler air hitting the glaze may cause
>crazing.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
| |
|
