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Advice on bending/warping


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I've been working on a piece that has a 6" tall,  3/4" wide cylinder and when I fire it with glaze it warps and bends slightly. Does anyone have any recommendations on how to prevent this? Should I do a solid coil instead of a tube? Some have advised inserting a wire or metal rod too but I've never used wire in my work before. 

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Hi and welcome to the forum!

A cylinder those dimensions that’s made out of a clay thats even a little pyroplastic is going to have issues however you construct it.

Can you tell us what you have done so far to get this, and what the piece is for? Our answers for a sculptural piece will be different than if the piece needs to be functional/hold water. Information on how you made it in the first place, what kind of clay you made it out of, how it was bisqued and glazed would be helpful. Was it fired in a particular way, and is it your kiln, or is someone else in charge of the firing?

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Thanks so much Callie. I'm making a miniature topiary. So there is a sphere that sits on top of the cylinder. I constructed it so that the cylinder goes about halfway through the sphere and then is secured in a base "planter" of about 3".  See the attached picture.

It's mostly glazed only with underglaze but there is a thin layer of clear on the cylinder which is what im wondering caused it to bend. It was all fired to cone 6. 

Thank you for your help!

Screen Shot 2022-04-16 at 7.36.18 PM.jpg

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@ZDillingham
“It's mostly
 glazed only with underglaze but there is a thin layer of clear on the cylinder which is what im wondering caused it to bend. It was all fired to cone 6.”

The shape itself being top heavy or supported on a relatively slender cylinder will be hard to keep string straight when fired. We had the same issue with making long stem wine glasses with truly fine stems. In the end it’s often easier to make it in two pieces and epoxy in place at final assembly. These are very high end delicate porcelain wine glasses so high temp food grade epoxy and very straight construction is a must. I mention because very high quality joined work can be made and often is an easier path to get your shape requirements. IMO, glaze did not cause this, the shape of the form makes it difficult to keep in plane during firing.

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For glaze to be a factor in warping, usually there has to be enough of it to exert enough tension to “overpower” the clay. The slight gloss you’ve got there isn’t going to exert enough pressure to make your tube move. 

It’s not the tube, it’s the weight of the ball on top of it.  If it was me, I’d fire the topiary ball on stilts. The marks can be easily hidden on the bottom. 

It’s a lovely piece!

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