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Warping of platters


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#1 Natania

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Posted 18 December 2012 - 09:45 PM

I have a ton of large, but thin, dark brown plastic bats on which I've just started to throw much larger platters than I've ever before attempted. The clay is too heavy for the bats, I think, and the bats bend when I am taking them off the wheel, no matter how carefully i try to pop the bats off the bat pins. this bends the platters and throws them out of round. Even if I try to correct them, i am sure the porcelain-like clay I am using will remember and warp that way in the firing. Any ideas about how to avoid this?

#2 bciskepottery

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Posted 18 December 2012 - 10:11 PM

Place clean newsprint on top of the platter and press it gently to the rim; then lift the bat from the wheel. The newsprint (and air trapped inside the platter) will help keep the rim shape while it is being removed.

Let the platter set up a bit before removing it from the wheel . . . reduce wheel speed and let it spin for a few minutes, then remove.

#3 neilestrick

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Posted 19 December 2012 - 10:10 AM

If they straighten out when you set them down, chances are they won't remember the warp. They're too wet to remember it at that point. My stuff warps a little when removing them from the wheel, and they never remember it.
Neil Estrick
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www.neilestrickgallery.com

neil@neilestrickgallery.com

#4 Marcia Selsor

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Posted 19 December 2012 - 12:43 PM

I use plywood bats for large platters and bowls. Try putting a bat on top of the lip and sandwich both bats as you lift the platter off the wheel.
I use this lifting practice to flip the platters several times as they dry.

Marcia



#5 Natania

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Posted 19 December 2012 - 08:47 PM

Thanks. I tried the newspaper trick today and it seemed to really help. I've also started waiting until the end of a throwing session of other items, and throwing one large platter then so I can leave it to dry up quite a bit before I pop the bat off the wheel head.

#6 Red Rocks

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Posted 06 January 2013 - 07:53 PM

I throw a lot of large bowls and platters and occasionally would have one warp. I believe what happens when you take it off the wheel can have an effect on the ultimate shape as well as anything that happens to it that might effect the rim until it is past the the green ware state.

I experimented with a lot of different bats before selecting the ones I use now. They are the Hydro Stone bats from the Ceramic Shop in PA. Here is their contact info:

The Ceramic Shop
3245 Amber St
Philadelphia, PA 19134
www.theceramicshop.com

I buy their seconds at a considerable discount. They don't always have them but they are definitely worth waiting for. They look and work like plaster bats but they are much stronger and don't have the chipping problems plaster has. Platters do not warp on these bats and the other big advantage is that the pieces release quite nicely from them so you do not have to hassle with cutting off a 20+ inch wet platter - which I find to be a huge hassle as well as another potential spot in the process to ding the rim or worse.




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