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Pottery/Bottom of Mug Leaking


QUESTION: During power outage I placed a pottery mug on woodstove to heat drink.  The mug got hot but I could up by the handle.  The mug now leaks on the bottom in three spots.  I put clear nail Polish all around the bottom but it still my mug a total loss or can I fix it somehow?

ANSWER: Dear Karen,

Thank you for your recent question. The mug is not a total loss, however, I need to know more information about it to assist you. First, are there any hairline cracks in the mug? Check the inside and outside using a magnifying glass. Second, is the mug glazed on the bottom, and if so, is it glazed completely, or just inside the foot ring? Third, is the mug made of porcelain or stoneware? If it is porcelain, the walls of the mug will be thin. If it is stoneware, the walls will be thick. Finally, is the mug handmade or commercially made? Commercially made are mugs that are sold in department stores. Handmade mugs are those made by yourself or purchased directly from a potter.

I look forward to your reply.

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

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

QUESTION: The mug is stoneware.  There are no hairline cracks. It is not glazed on the bottom...the glaze just barely touches the bottom.  I have covered about 1/2 inch of the bottom around the edge with clear nailpolish hoping to stop the luck.
thank you for your attention to my question

Dear Karen,

Thank you for your reply. It is not uncommon for a mug to leak on bottom, however, this normally occurs with earthenware clay and not stoneware. In this situation, the clay that was used for your mug probably had a high content of grog in the clay body and when it was heated over the wood stove, the grog caused an expansion of the clay, separating the molecules of the clay, causing the leak. Wood stoves, under the right condition can get as hot as a raku kiln and therefore, your mug was essentially being re-fired on bottom.

The only way to repair the mug is to have it fired again to low fire and allowed to cool normally. Re-firing will cause the clay molecules to re-position and seal the leaking areas. If you have a pottery studio located in your area, I suggest you take the mug to them and have them do a low fire on the mug. If you can't find a studio in your area, contact me again with your location and I will be happy to assist you in locating one.

I hope this helps you. If you have further questions, please contact me again at any time and I will be glad to help. Always at your service.

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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