Glaze Fit, Clay Bodies And Cones

[Plattypus]

I teach Middle School Art. For years I used Amaco clay without much satisfaction. A couple of years ago I switched to a Standard clay because my High School Ceramics colleague was using it. Standard #306 I believe that it's range is 4-10. We have been bisque firing it still at cone 04 as we had done in the past... many of the glazes we use direct that (and I figured my colleague knew better than me)

 

Last year I purchase some cone 6 glazes and much prefer their effects. My colleague doesn't want to fire in this range due to the increase in kiln deterioration.

I read the recent posts on firing and now understand what the pinging is about...

 

Since my clay order for next year has been placed and is still the standard 306, to what cone should I bisque and which glaze temps are best? The majority of my glazes are 06-05. Can someone recommend a best case scenario for my situation? AND do you have another recommendation for future years? I would prefer a warm color clay body, would like nice interesting surfaces and can't afford to be to too rough on my kilns... the only control I have for the kiln is time and/or the Dawson kiln sitter.

[Lucille Oka]

I teach Middle School Art. For years I used Amaco clay without much satisfaction. A couple of years ago I switched to a Standard clay because my High School Ceramics colleague was using it. Standard #306 I believe that it's range is 4-10. We have been bisque firing it still at cone 04 as we had done in the past... many of the glazes we use direct that (and I figured my colleague knew better than me)

 

Last year I purchase some cone 6 glazes and much prefer their effects. My colleague doesn't want to fire in this range due to the increase in kiln deterioration.

I read the recent posts on firing and now understand what the pinging is about...

 

Since my clay order for next year has been placed and is still the standard 306, to what cone should I bisque and which glaze temps are best? The majority of my glazes are 06-05. Can someone recommend a best case scenario for my situation? AND do you have another recommendation for future years? I would prefer a warm color clay body, would like nice interesting surfaces and can't afford to be to too rough on my kilns... the only control I have for the kiln is time and/or the Dawson kiln sitter.

 

Standard also has beautiful glazes that are well suited for their clays. I would recommend Standard glazes for Standard clay. Before your purchases ask which glazes contain zinc (which can affect your underglazes if you are using any).

Straight firing of bisque and gloss isn't ‘rough’ on a kiln.

Your clay has a large firing range so I recommend testing to see what happens with your chosen glazes. Cone 04 bisque is a norm but check with Standard about the recommended bisque firing temperature of their clays. Maturation point of the glaze should coincide or correspond to the maturation point of the clay. You can get some beautiful glaze results at Cone 5. If a kiln is rated as such it can be fired high and/or low. Do you have the kiln manual?

 

 

[bciskepottery]

Since the majority of your glazes are ^05 and ^06, then continue to bisque at ^04. I believe most low fire glaze manufacturers recommend bisquing a minimum of one cone higher than what your fire for glazing.

 

For the future, your real challenge is not picking a clay body, but getting your high school counterpart to understand firing to ^6 is not going to increase the rate of deterioration of your school's kiln. Assuming the kiln is in good condition and is rated to fire to ^6 or higher, then you will not be overstressing the kiln or its elements or leading the kiln to a premature death. My sense is you are more likely to damage elements from a too thick, not bone dry piece blowing up inside the kiln than you are from increasing the glaze firings to ^6.

 

Standard has a wide selection of mid-range clay bodies that work well, have nice color, and are vitrified at ^6. I like their 112, Speckled Brown and 308, Brooklyn Red. Their 266 Dark Brown is great, but would not suggest using that with children due to the addition of manganese in the clay body.

[Plattypus]

I teach Middle School Art. For years I used Amaco clay without much satisfaction. A couple of years ago I switched to a Standard clay because my High School Ceramics colleague was using it. Standard #306 I believe that it's range is 4-10. We have been bisque firing it still at cone 04 as we had done in the past... many of the glazes we use direct that (and I figured my colleague knew better than me)

 

Last year I purchase some cone 6 glazes and much prefer their effects. My colleague doesn't want to fire in this range due to the increase in kiln deterioration.

I read the recent posts on firing and now understand what the pinging is about...

 

Since my clay order for next year has been placed and is still the standard 306, to what cone should I bisque and which glaze temps are best? The majority of my glazes are 06-05. Can someone recommend a best case scenario for my situation? AND do you have another recommendation for future years? I would prefer a warm color clay body, would like nice interesting surfaces and can't afford to be to too rough on my kilns... the only control I have for the kiln is time and/or the Dawson kiln sitter.

 

 

Standard also has beautiful glazes that are well suited for their clays. I would recommend Standard glazes for Standard clay. Before your purchases ask which glazes contain zinc (which can affect your underglazes if you are using any).

Straight firing of bisque and gloss isn't ‘rough’ on a kiln.

Your clay has a large firing range so I recommend testing to see what happens with your chosen glazes. Cone 04 bisque is a norm but check with Standard about the recommended bisque firing temperature of their clays. Maturation point of the glaze should coincide or correspond to the maturation point of the clay. You can get some beautiful glaze results at Cone 5. If a kiln is rated as such it can be fired high and/or low. Do you have the kiln manual?

 

 

 

[Plattypus]

Thanks for your answers. I am relieved to hear them. If I understand correctly, should I consider changing the bisque cone of the clay to the cone nearest the glaze we are going to use? I could 04 the bisque for the low fire glazes and do a 4 or a 5 for the cone 6 glazes. I believe I do have the manual. I think the kiln is technically a "glass" kiln based on other conversations I've had with Bruce Dehnert from Peter's Valley here in NJ. I have fired my kiln as hot as cone 10 but only one time (turned out it was a mistake on my part but it did bend the cone)

[ceramicgirl]

While Standard glazes will work nicely on Standard clay, consider other glazes as well. Mayco has low fire glazes that have a wide firing range and go up to cone 6 very nicely. Their website has pictures of some of the outcome to the higher firing. Try some of the Stroke & Coats, Jungle Gems, and Elements.

[Lucille Oka]

 

 

Thanks for your answers. I am relieved to hear them. If I understand correctly, should I consider changing the bisque cone of the clay to the cone nearest the glaze we are going to use? I could 04 the bisque for the low fire glazes and do a 4 or a 5 for the cone 6 glazes. I believe I do have the manual. I think the kiln is technically a "glass" kiln based on other conversations I've had with Bruce Dehnert from Peter's Valley here in NJ. I have fired my kiln as hot as cone 10 but only one time (turned out it was a mistake on my part but it did bend the cone)

 

 

 

 

 

 

 

 

 

 

Cone 04 is 'standard' for bisque firing for most clay bodies, unless the clay manufacturer states otherwise. The idea of the bisque firing basically is to allow the ware to become firm enough to be handled, remain porous enough to accept the glaze, and to release the gases in the clay that can cause glaze defects. Cone 4 or 5 bisque maybe a little too hard and may make glazing difficult. I suggest testing to see how the bisqued clay accepts the glaze at that temperature.

 

If you have the manual check to see if the 'glass kiln' is rated for medium range (Cone 5-6) and high firing (cone 10).

 

If not, then you

are

over firing and stressing the kiln and the elements.