[Clayart] Offgassing bisque

Antoinette Badenhorst porcelainbyantoinette at gmail.com
Sun Jan 30 15:30:24 UTC 2022

 Bryan, try only water in the bisque. I cannot say what will happen after the 2 nd fire if you only use water, but in the bisque the clay is soft , but abrasive enough to smooth itself. I keep the bisque powder. It is a natural  grog.  

Best wishes, 
Antoinette Badenhorst

International Academy of Ceramics
Mississippi Arts Commission

> On Jan 29, 2022, at 8:37 PM, Bryan Johnson <bryj at cheqnet.net> wrote:
> Snail mused about temp increase. I see bubbles even before starting the
> tumbler. These could be just air displacement.
> They only get slightly above room temperature.
> JM  I do a low bisque, around 010. The pieces are quite smooth after 8 to
> 24 hours with no additional grIit. Clay with grog probably wouldn't work.
> After high fire they are tumbled again. The polishing after bisque
> eliminates the need for grit. It might speed up the polishing to use fine,
> or other finishing compound, but not needed. I like not having to deal with
> / risk getting SiO in my clay reclaim.  I like to change the water
> occasionally.
> Bryan Johnson
>> On Sat, Jan 29, 2022 at 5:47 PM Snail Scott <claywork at flying-snail.com>
>> wrote:
>>>> On Jan 28, 2022, at 8:26 AM, Bryan Johnson <bryj at cheqnet.net> wrote:
>>> When I tumble polish bisqued colored porcelain jewelry I need to "burp"
>> the
>>> barrels after an hour or so due to the gas given off by the porcelain.
>> What
>>> is the gas?
>> Could the interior air have warmed that much from friction; enough to
>> create a noticeably larger air volume?
>> Can you aim a temperature gun at it, and compare the exterior temps at the
>> start and finish?
>> -Snail
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