Ababi on thu 19 feb 04
I want to build this letter on Ivor's reply to my letter.
The glaze guru goes down to the atoms level. sometimes to the uranium whi=
ch
is too far to my test...
The glaze addict is mixed up from a letter like the one bellow.
The glaze addict goes only to the molecular levels and sometimes even
remember how to write them properly.
Do I know when the sodium melt? may be. Yes of course!
I explain my knowledge this way: I know more than I can explain and I can
explain more than I know.
I realized some rules I also realized the way to break these rules.
So one hand thank you Ivor
On the other hand: I shall keep using my experience and my " surface" ( o=
f
glaze) radar to read how to fix or "ruin" the ceramic-ware- coating.
Ababi Sharon
Glaze addict
Kibbutz Shoval -Israel
http://ababi.active.co.il
----- Original Message -----
From: "Ivor and Olive Lewis"
To:
Sent: Wednesday, February 18, 2004 5:51 AM
Subject: Re: Layering glazes. Source of Practical Information.
Dear Ababi,
The temperature I gave, in the two common scales (700=BAC ~1300=BAF) ,
would be predicted from statements which inform us that mixtures of
oxides provide glazes which fuse due to eutectic melting.
However, my humble experience is that glazes compounded from Soda
Felspar, Potash Felspar or Nepheline Syenite struggle to mature at any
temperature below 1200 =BAC ~2192=BAF even though they may show signs of
melting. Things change when you add one of the Boron Compounds to the
recipe.
In theories given to us by "Glaze Masters", we should be able to mix
Potash Felspar, Quartz and Kaolin and get a total melt at 985=BAC
~1805=BAF from a recipe containing 9.5%K2O, -10.5% Al2O3 - 80% SiO2. I
could not predict this mixture would give a satisfactory glaze.
Similarly, and contrary to what we might expect, using Soda Felspar
with Quartz and Kaolin and the following oxide values; 8% Na2O, 14%
Al2O3, 78% SiO2 melting, in theory, should happen at 1050=BAC ~1922=BAF.
but I would not lay bets on the event.
Layering glazes is not the same as mixing glazes. Used with thought
and knowledge derived from trials of layering by dipping, spraying,
brushing or combining such methods this technique can give
outstandingly attractive and exciting results. The latter part of Greg
Daly's book, "Glazes and Glazing Techniques" , ISBN 0-86417-502-7, is
devoted to this very process.
Best regards,
Ivor Lewis. Redhill, South Australia
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Ivor and Olive Lewis on fri 20 feb 04
Dear Ababi,
Thanks for the tip off.
Be glad when it cools down and I can get into the studio to work with
real rather than "Virtual" clay and glazes.
Best regards,
Ivor
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