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Pottery/Cone 06 Clay Food Safety Issue

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Question
Hi,
I have only just recently been using low-fire clay's and glazes and I'm having fun.  But when first leaning pottery The schools taught us with only high-fire clay and glazes,(cone 6).  We were told that cone 6 and provided the glaze was lead free, was food safe and could be used. But they never really addressed low-fire, cone 06.  It just wasn't available to us. I am aware of many reasons why high fire would not be foodsafe...ie, lead in Glaze, pinholes and grazing, cracks ect.  I just need to know that if I make a mug out of low fire clay and use the appropriate glaze (lead free and smooth) that I can drink tea out of it.  And if I glaze just the inside of the mug and only semi decorate the outside with glaze, can I use the mug and feel food safe? Provided that the portion the tea sits in is fully covered by glaze?

Answer
Dear Roxanne,

    Thank you for your recent question. Low fire clay bodies are a porous clay that is often confused when used with the term food safe. Most low fire clay bodies are food safe and can be used for the purpose you are intending. However, it is primarily the glaze body that is of concern. As I have covered before in answering questions about low fire clay and glazes, the glaze safety issue implies to the raw materials that are in the glaze as well as the final outcome of the glaze body upon firing.

    As with any medium or high fire clay and glaze, the maturing temperature is most important to assure a piece is fired sufficiently enough to render it food safe. Choosing a clay and glaze body that does not have any raw materials with hazardous ingredients is a must. Check your clay and glaze manufacturer to determine if the clay and glaze bodies you are going to use are safe to use with food products.

    As for the decoration method you are choosing, yes, you can just decorate the inside of the cup for placement of the tea, however, where your lips touch the edge of the cup may be an area where bacteria will collect. Because Cone 06 clay is porous, every time you drink from the cup, your mouth will come in contact with tea residue along the edges of the cup. If you intend on making this cup just for you, and using a scrub brush on the un-glazed edges, then yes, it would be safe. However, the better choice would be to glaze the entire cup, even if you only glaze the outside with clear, just to be on the safe side, if someone else uses your cup or if you failed to scrub it, even one time.

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

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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