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crystal glazes cone six ox lllong leeeeeeetter #2

updated sun 13 apr 03


Ababi on sat 12 apr 03

So how to avoid the running glaze in the bottom of the ware?
Fara Shimbo in her book offers to apply a different glaze on the bottom of the
ware. Bottom I mean of the ware, nowhere else!
I tried several glazes, high alumina glazes.
Please see
The Laguna porcelain which warps easily react beautiful to the connection between
my crystal 11 and my waxy red brown. The Limoges porcelain reacts not so nice .
On the other hand the Limoges Does not warp.

This glaze:

Cone 6 1222 deg.C. -

EPK Kaolin 19.70
FRIT 3110 26.90
zinc oxide 7.70
SILICA 13.90
Feldspar Soda F7 7.70
Wollastonite 10.60
Cobalt Oxide 2.00
Copper oxide black 2.00
Nickel Oxide 2.00
Manganese Dioxide 0.50

Seger Weight%
KNO 0.262 5.82%
CaO 0.335 6.44%
MgO 0.012 0.16%
ZnO 0.286 7.97%
Li2O 0.105 1.08%
Al2O3 0.401 14.00%
B2O3 0.030 0.73%
SiO2 3.093 63.73%
TiO2 0.003 0.08%
K2O 0.022 0.70%
Na2O 0.241 5.12%
Al:Si 7.72
Expan. 7.36
ST 366.23
Try to use Custer instead of F-7 in the same amounts or 0.5% more.

You can see one the small saucer, the outside it is fine while inside there are some
pinholes or boiled parts. I do not know the reason however I need it for outside or
bottom of (wares) therefore it is fine.
In most tests In the last crystal firing the meeting between the crystal glaze and the
"bottom" glazes was fascinating - even if the crystal glazes did not succeed the
connection was good and beautiful.

The pictures are not so good yet good enough to demonstrate what I mean.

* * *

Crystal glazes cone six ox lllong leeeeeeetter #3
The reason it took me so long to finish the letter was that I was confused myself.
Took me three weeks to find the words:
If you are happy with your crystal glazes fine go on the way you do.
If you are not so happy try this:
Laguna English porcelain warps? Try to add molochite.
I made one test. I added 10% molochite was good. nice crystals no warping. I am not
sure it would be as beautiful as the original. On the other hand the glaze that was
boiled one the original claybody became fine on the reinforced claybody.
I tried to apply slip both WB04048 of Vingerling Holland and the Laguna porcelain over
a groged claybody in the greenware stage. The first slip in one case was good in the
second ware cracked.
The Laguna porcelain as slip cracked. The blue glaze in this page is a crystal glaze
that as you can see has not succeeded.
I have from the happy days of the raku a claybody based on V.C. Raku claybody. It
makes the crystal glaze appearance unique.
Any fine raku claybody could be tested, the results might be fascinating. The same
with different porcelains.

Crystal glazes cone six ox lllong leeeeeeetter #4: in a separate letter
Ababi Sharon
Glaze addict
Kibbutz Shoval Israel
and also