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more info. on crawling glaze.

updated tue 23 mar 04

 

=?iso-8859-1?q?Iben=20Vedel?= on thu 18 mar 04


Hi everyone.
First thank you to everyone that replied on my 2 emails about crawling glazes and La Borne in France.
And then some more info on the firing of the copper glaze that crawled, so as not to keep people in the dark ;0))

The gas kiln is fired with 150 C an hour, Reduction starts at 800 C and continues all through the firing, the end temp. is 1250 C.
We soak between 15 to 25 minutes depending on how the end of the firing is.
The kiln is then left to cool down.

Here is the recipe again:

Turquise/Oxblood glaze.
> Potash Feldspar 420
> Whiting 210
> Silica 210
> Kaolin 100
> Talc 50
> Tin Oxide 75
> Copper Carbonate 10

Iben



*Brussels_where the Pots do their fire dance and the glazes run Wild* ivedel@yahoo.com





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Ron Roy on mon 22 mar 04


Hi Iben,

First - some glazes need to be completely dry before firing to reduce the
chance of crawling.

Adding some bentonite (2%) might help in this case.

Kaolins do not usually form a tough glaze coat so changing to a ball clay
will sometimes help. I've redone you glaze with ball clay if you care to
try it out - let us know if any of the above work.

Pot Spar - 420.0
Whiting - 210.0
Silica - 173.0
Ball clay - 130.0
Talc - 50.0
Tin - 75.0
Copr Carb - 10.0
Total - 1068.0

RR


>First thank you to everyone that replied on my 2 emails about crawling
>glazes and La Borne in France.
>And then some more info on the firing of the copper glaze that crawled, so
>as not to keep people in the dark ;0))
>
>The gas kiln is fired with 150 C an hour, Reduction starts at 800 C and
>continues all through the firing, the end temp. is 1250 C.
>We soak between 15 to 25 minutes depending on how the end of the firing is.
>The kiln is then left to cool down.
>
>Here is the recipe again:
>
>Turquise/Oxblood glaze.
>> Potash Feldspar 420
>> Whiting 210
>> Silica 210
>> Kaolin 100
>> Talc 50
>> Tin Oxide 75
>> Copper Carbonate 10
>
>Iben

Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513