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Pottery/Glaze Firing Cone 04-06 Clay


QUESTION: I'm new to firing bisque and glaze on my own. I've only ever taken classes and had all resources supplied for me. So I now have a question, because until now I've never had to think about it. My clay is cone 04-06, I bought glazes that are cone 4/ this going to be a problem? Suddenly I'm worried that the clay might melt if I use high-fire glaze on low-fire clay. Is that correct? Please help! My pieces are intended to be Christmas presents and I don't want to ruin them!

ANSWER: Dear Melissa,

Thank you for your recent question. Yes, you are correct. You can not use the cone 4/6 glaze on a cone 04/06 clay body. The maturing temperature of the clay body is much lower than the maturing temperature of the glaze. You will need to purchase a low fire glaze to use on your clay. If you were to use the high fire glaze on the low fire clay body, your clay would melt.

I hope this assists you in answering your question. If you have further questions, please feel free to contact me at any time. I am always at your service.

Ms. Ti Phillips
Earth Stoke 'N Fire Pottery Studio and Artist Retreat

---------- FOLLOW-UP ----------

QUESTION: What if I fired the high fire glazes to only cone 04-06? I know the colors would probably be very different, but would it still work? The pieces include mugs and bowls.

Dear Melissa,

Thank you for your follow up question. Firing the cone 4/6 glazes to only cone 04/06 will render the glazes unsafe to use on the mugs and bowls. It will also render the glaze a powder look, instead of a sheen or matte to glossy surface, depending on the glaze you are using. Finally, under firing a glaze prevents the fusion that must occur between the clay and glaze, which causes the clay and glaze to become one structure, instead of two separate surfaces.

My suggestion to you is to purchase the cone 04/06 glazes that will give you the look you want. I know that it is close to Christmas, but you do want the pieces to be fired correctly so that they will be safe to use and look wonderful as gifts.

If you can't purchase the glaze and fire before Christmas, I suggest you wrap an envelope with a message to those you wish to give your mugs and bowls to, explaining their gifts will be coming. I am sure this is a bit disappointing, but when you do deliver them, you will enjoy giving them much more than giving potentially dangerous pieces.

If you have already glazed the pieces, you can wash them under warm water and use a tooth brush to remove the glaze. Let them dry and re-apply the new glaze.

I'm sorry that you must do this, but it is the only way to ensure the glaze is safe and suitable for functional ware.

Once again, thank you for your follow up question. If you have further questions, please feel free to contact me again any time. I am always at your service. Much luck to you.

Ms. Ti Phillips
Earth Stoke 'N Fire Pottery Studio and Artist Retreat


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Ti Phillips


Will answer any questions on hand building, wheel, glaze, firing. Speciality questions to include those in glaze calculation and development, firing techniques. Please do not send questions on identifying pottery. Although I would love to add this to my question topics, I have a retreat to run as well as the studio and volunteering on AllExperts, and therefore do not have the available time to research indentification and marks. Thank you for understanding.


Experience includes 30 years in pottery design and education. Have taught online and studio classes worldwide for the last 20 years. Own a pottery retreat specializing in firing techniques. Have 12 years solid experience in glaze calculation and formulation as well as problem solving in glaze chemistry. I am the first potter in the United States to have developed a complete package of pottery equipment blueprints for a studio. The blueprints include wheels, kilns, studio furniture, wedgeboards, raku kilns, slab rollers, ball mills and studio tools.

Alliance of Pottery Artists Worldwide Association

Ceramic Industry - PPP Wyndstryder Press - Pottery Journal

University of Sciences and Art's of Oklahoma, studied under Professor Jaymes Dudding.

Awards and Honors
Potter of the year with APAWA, various awards for showmanship and design.

Past/Present Clients
Available upon request.

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