Ron Roy on fri 24 sep 10
Cristobalite still forms on the way up and you can still have too much =3D2=
0
- which is why it's important to understand why it forms and how to =3D20
deal with it when it does.
Peter's article is one of the most important for those working with =3D20
high fire stoneware clay bodies. To try to make a stoneware clay =3D20
without his information is folly - especially with all the =3D20
misinformation we have inherited from those who thought knowing about =3D20
clay and glazes on a technical level was sissy stuff.
Correcting bad body design by slow cooling is really not the best =3D20
answer. Not that slow cooling is a bad idea - just not the right =3D20
answer for cristobalite in your clay.
RR
Quoting Lee Love :
> On Fri, Sep 24, 2010 at 12:59 PM, Ron Roy wrote:
>> Hi Vince,
>>
>> Lots of bisque dunting happens at the quartz inversion - I have to
>> correct that and say almost all happens at 573C - there is usually no
>> cristobalite present in bisque because it forms above 1100C.
>
> This is a reason why Mick Cassion crash cooled to 1100*C, it reduces
> cristobalite formation in high silica bodies. It also promotes red
> color in high alumina clay and glazes. I primarily did it for red
> color on unglazed shigaraki clay.
>
> http://www.google.com/images?hl=3D3Den&rlz=3D3D1C1AVSX_enUS386US386&q=3D3=
DMick+C=3D
asson&um=3D3D1&ie=3D3DUTF-8&source=3D3Dog&sa=3D3DN&tab=3D3Dwi&biw=3D3D1028&=
bih=3D3D613
>
> --
> =3DC2=3DA0Lee, a Mashiko potter in Minneapolis
> http://mingeisota.blogspot.com/
>
> =3DE2=3D80=3D9CObserve the wonders as they occur around you. Don't claim =
them. F=3D
eel
> the artistry moving through and be silent.=3DE2=3D80=3D9D --Rumi
>
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