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Pottery/Bisque Fired Clay Yellow in Color

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Question
I recently bought a kiln and am new at firing by myself. I fire a mid-fire white clay body and ran a bisque load at a cone 05. My bisque turned a yellow color and Im wondering what I did wrong and if I glaze with a clear coat will it stay yellow after the second firing?

Answer
Dear Rachel,

    Thank you for your recent question. You have done nothing wrong. The clay body has not reached its matured temperature. The yellowing is most likely from the iron content in the clay. Once the clay has been fired to it's maturing mid-cone range, it should be white, no matter what color glaze you apply.

    Most clays have iron in their content. When they are worked, the clay is usually a darker color than what it will be when it is fired to maturing temperature. As the clay is fired to cone 05, there is still enough iron in the clay to maintain a yellow or reddish color. When the clay is glaze fired or fired without glaze to it's maturing temperature of cone 6, it will burn off the excess iron and the clay will be white.

    Don't worry, you have done nothing wrong. Continue with your glazing as planned and fire to the maturing cone.

    I hope this answers your questions. If you have further questions, please feel free to contact me again in the future. I am always at your service. Good luck to you.

Sincerely,
Ms. Ti Phillips
Earth Stoke 'N Fire Pottery Studio and Artist Retreat
www.earthstokenfire.com

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Ti Phillips

Expertise

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

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.

Organizations
Alliance of Pottery Artists Worldwide Association

Publications
Ceramic Industry - PPP Wyndstryder Press - Pottery Journal

Education/Credentials
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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