Alisa and Claus Clausen on thu 20 jul 00
This glaze was one given by Marica Selsor May 11 in her list of cone 6 =
reduction glazes.
Thank you.
=20
I fired it on light grey, mid range stoneware, but oxidation
=20
Receipe
EPK 23
Dolomite 20
Neph. Syn. 38
Silica 4
Whiting 4
Gerstely Borate 10 =20
=20
Tests resulted in a semi mat clear which crazed. Small to large cracks =
over entire surface.
=20
Would the difference of reduction to oxidation cause this fault?
I would like to much further test this glaze and all the others she =
posted. Especially this one as=20
a base for all the coloring suggestions she lists.
=20
Best regards,
Alisa in Denmark.
Marcia Selsor on thu 20 jul 00
Dear Alisa,
Jeff Lawrence fired them in reduction with great success. I think it
crazed because it doesn't fit your clay body. I never had it craze on
our stoneware. Do you think the electric kiln cooled faster than a large
gas? That might be another reason.
Marcia
Alisa and Claus Clausen wrote:
>
> This glaze was one given by Marica Selsor May 11 in her list of cone 6 reduction glazes.
> Thank you.
>
> I fired it on light grey, mid range stoneware, but oxidation
>
> Receipe
> EPK 23
> Dolomite 20
> Neph. Syn. 38
> Silica 4
> Whiting 4
> Gerstely Borate 10
>
> Tests resulted in a semi mat clear which crazed. Small to large cracks over entire surface.
>
> Would the difference of reduction to oxidation cause this fault?
> I would like to much further test this glaze and all the others she posted. Especially this one as
> a base for all the coloring suggestions she lists.
>
> Best regards,
> Alisa in Denmark.
>
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--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/spain99.html
http://www.silverhawk.com/ex99/selsor/welcome.html
Ron Roy on sun 23 jul 00
Hi again Alisa,
The crazing is probably related to the clay body. Fast firing or cooling
will have an effect as well. I have reformulated to lower the
expansion/contraction - I think it will still look the same - use your
local spar for the G200.
Frit 3134 - 15.0
Neph Sy - 13.0
G200 - 14.0
Dolomite - 24.0
EPK - 32.0
Silica 2.0
Total - 100.0
Ratio - 3.95 (original is 3.74)
Expansion - 534.09 (581.62)
If I am going to keep working on your glazes I will need the analysis for
your frit - the molecular formula you included is not good enough.
Let us know if it works please.
RR
>This glaze was one given by Marica Selsor May 11 in her list of cone 6
>reduction glazes.
>Thank you.
>
>I fired it on light grey, mid range stoneware, but oxidation
>
>Receipe
>EPK 23
>Dolomite 20
>Neph. Syn. 38
>Silica 4
>Whiting 4
>Gerstely Borate 10
>
>Tests resulted in a semi mat clear which crazed. Small to large cracks
>over entire surface.
>
>Would the difference of reduction to oxidation cause this fault?
>I would like to much further test this glaze and all the others she
>posted. Especially this one as
>a base for all the coloring suggestions she lists.
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Jeff Lawrence on tue 25 jul 00
Hello Alisa and Marci,
I really like the surface on Marci's mat and Ohata red, but also suffered
quite a bit of delayed crazing on both. My clay was sandy and some of the
clay poked through the mat, too. I think higher viscosity with additional
epk might help that as well as bring the expansion down.
I've got some alterations calculated but haven't fired cone 6 lately. When I
do, I'll post them and the results.
Best,
Jeff
Jeff Lawrence vox: 505 753 5913
Sun Dagger Design fax: 505 753 8074
18496 US HWY 84/285 jml@sundagger.com
Espanola NM 87532 www.sundagger.com
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