SUBSCRIBE Clayart Roger Symes on sun 18 dec 11
I have recently purchased a second-hand Cromartie 125 WH kiln, two recent=
=3D
glaze firings have a small number of pinholes in the glaze towards the
bottom of the pots. The controller with this kiln only allows one ramp
followed by maximum power & a soak. I am using a stoneware clay (11=3D
06
White St Thomas 1160-1300 degrees centigrade (2160 centigrade 2372
fahrenheit) & Spectrum Nova dipping glazes. The pots were bisqued t=3D
o 1023
degrees centigrade( 1873 fahrenheit)
For these two firings I used the following firing schedule:-
First Ramp 5 hours to 600 degrees centigrade (1112 fahrenheit)
Final Temperature 1200 degrees centigrade((2192 fahrenheit)
A soak for 20 minutes.
Using the same clay & glazes in my previous small 3kw kiln I did not =3D
have
this problem.
I would welcome some advice as to an alternative firing schedule or any
other comments.
ronroy@CA.INTER.NET on mon 19 dec 11
Hi Roger,
Probably because the clay is thicker down there - slowing your firing
towards the end will help it catch up - also shelves keep bottoms
cooler if you fire too fast. Slow down to 50C per hour for the last
100C - or
Try a longer soak.
Make sure there is enough fresh air (oxygen) when bisquing to burn out
all organics if the body has iron in it.
Let me know if you need more - this should be easy to cure.
RR
Quoting SUBSCRIBE Clayart Roger Symes :
> I have recently purchased a second-hand Cromartie 125 WH kiln, two recent
> glaze firings have a small number of pinholes in the glaze towards the
> bottom of the pots. The controller with this kiln only allows one ramp
> followed by maximum power & a soak. I am using a stoneware clay (1106
> White St Thomas 1160-1300 degrees centigrade (2160 centigrade 2372
> fahrenheit) & Spectrum Nova dipping glazes. The pots were bisqued to 10=
23
> degrees centigrade( 1873 fahrenheit)
> For these two firings I used the following firing schedule:-
> First Ramp 5 hours to 600 degrees centigrade (1112 fahrenheit)
> Final Temperature 1200 degrees centigrade((2192 fahrenheit)
> A soak for 20 minutes.
> Using the same clay & glazes in my previous small 3kw kiln I did not have
> this problem.
> I would welcome some advice as to an alternative firing schedule or any
> other comments.
>
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