pieces warping during glaze firing
Posted 30 March 2013 - 07:43 PM
Posted 30 March 2013 - 09:47 PM
As for the platters, in general, make sure you are compressing the slabs, rolling them in all directions . . . especially if you are using a slab roller to make them. Also, after rolling, take the ware board with slab on it and drop it flat against the floor from about mid-waist high -- that will compress the slab. Handle slabs minimally to prevent warping. If you could tell how you make your slabs, it might be easier to diagnose what is going wrong.
Posted 31 March 2013 - 06:17 PM
The platters -- I roll out my slab with a slab roller. I reposition the slab every couple of rolls, turning it at right angles and sometimes flipping it over. I sometimes drop the ware board from about waist to chest height, sometimes just drop it onto a table a few times until it has "settled in". Should the slab be thicker than 1/4 inch? I guess dropping it once from waist high is preferable to 4 drops on a table...
If I'm glazing at Cone 6, could I bisque hotter than 04?
Lots of learning to do!
Posted 31 March 2013 - 07:05 PM
The other obvious things are to thin of slabs and or non flat warped shelves??
Maybe the table is not flat as well?Many wood tables are not flat- all these things can be checked out.
What size are these platters? are they round or square and do they have a lip?
Posted 31 March 2013 - 09:03 PM
As Mark has said, your platters, and all clay shrinks as it dries. I dry all of my pots upside down so the rims dry slower. My platters, which are thrown, I dry on flat particle board batts. I also cover my leather hard pieces under plastic. You might be drying your pieces too quickly. The bigger the piece, the more drying issues.If your pieces are hanging over a kiln shelf, they will also warp.
Posted 01 April 2013 - 06:18 AM
Posted 02 April 2013 - 10:13 AM
As a general rule, I always follow the mantra 'the flatter it is, the slower it dries' also, if you have to invert, or do something to assist with drying (waxing handles and lugs, waxing rims, inverting and drying on foam, etc) ... do it.
Posted 04 April 2013 - 06:46 PM
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