Lee Love on tue 29 jul 08
On Tue, Jul 29, 2008 at 1:14 PM, Bill Merrill wrote:
> If Talc is used as a flue in a stoneware body, it will accept heat
> difference better than if feldspar is used as a flux. I always use talc
> in my stoneware body as talc also promotes an orange color to the clay
> when in reduction and is a good choice for casseroles or baking dishes.
> I use spar as a flux when I am going to salt fire.
I was told that Donabe flameware has lithium in it.
--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/
"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi
Bill Merrill on tue 29 jul 08
If Talc is used as a flue in a stoneware body, it will accept heat
difference better than if feldspar is used as a flux. I always use talc
in my stoneware body as talc also promotes an orange color to the clay
when in reduction and is a good choice for casseroles or baking dishes.
I use spar as a flux when I am going to salt fire.
=20
Bill
Ivor and Olive Lewis on thu 31 jul 08
Talc is a remarkable material, a hydrated Magnesium Silicate. It is a
refractory in its own right but, when heated to remove the chemical
water, it converts to Enstatite, an even more heat resistant material.
I seem to recall that the porcelain insulator of an Auto Spark Plug is
a high talc, high Alumina body of remarkable thermal shock resistance
as well as providing electrical insulation.
Potash Felspar in a clay body promotes the formation of a glaze with
Sodium Chloride. But the high Coefficient of Expansion leads to
widespread crazing and subsequent weeping if the body is not mature
before glazing commences.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Ron Roy on fri 1 aug 08
All the literature I have read says you will get cristobalite in a high
fire body unless you flux with enough KNaO - I offered to measure a bar
before Bill - happy to do it - all I need is a couple of small samples -
easy to do - if I don't find any cristobalite I'll publish that.
Let me know if you need to know how to make the samples.
RR
>If Talc is used as a flue in a stoneware body, it will accept heat
>difference better than if feldspar is used as a flux. I always use talc
>in my stoneware body as talc also promotes an orange color to the clay
>when in reduction and is a good choice for casseroles or baking dishes.
>I use spar as a flux when I am going to salt fire.
>
>
>
>Bill
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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