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kiln wash project...

updated sat 8 nov 97


Talbott on fri 17 oct 97

I am trying to develop a kiln wash formula that will not flake in a cone 10
reduction firing. Someone suggested using collodial silicon as the bulk of
the formula. All suggestions will be appreciated... Marshall


Details will be forth coming!!!

Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
Clayarters' Live Chat Room, Fri & Sat Nites at 10 PM EDT & Sun at 1 PM EDT

Jean Silverman on thu 23 oct 97

At 10:21 AM 10/17/97 EDT, you wrote:
>----------------------------Original message----------------------------
>I am trying to develop a kiln wash formula that will not flake in a cone 10
>reduction firing.

The most reliable kiln wash I know of is the formula I got some time ago at
a kiln workshop given by Harry Dedell: half EPK and half alumina hydrate by
volume, mix to taste. It has never flaked on me. If your glazes don't run,
one coat can last years.
Jean Silverman
Studio Potter Network
41 Neal Mill Road
Newmarket NH 03857

Debby Grant on sun 26 oct 97

Hi Jean,

Do you really mean mix by volume and not by weight? Have I been
doing it wrong all these years?

Debby Grant

Jean Silverman on sat 1 nov 97

At 12:26 PM 10/26/97 EST, you wrote:
>----------------------------Original message----------------------------

>Do you really mean mix by volume and not by weight? Have I been
>doing it wrong all these years?
>Debby Grant

Debby (and others),

Yes, I really mean by volume! Usually I mix roughly two cups of al.hydrate
and two cups EPK for a batch--my kiln wash container is rather small. The
original recipe I got as a novice potter was a mix of silica and EPK by
volume, which gave me years of grief by flaking off shelves and landing
inside bowls, etc. Once I learned about al.hyd., my kiln was ever after
flake-free. A good coating of kiln wash now stays put for years, unless and
until glaze drips over it. The coating lifts with the drip and I fill in the
bare spot before stacking the next kiln load.

Seems to me that if you measure by weight, you'll have a lot more EPK than
al.hyd., and since it's the al.hyd. that keeps the wash refractory, you'd
want more of it. no doubt I've got it all backwards, but what I do know is,
it works!


Fay & Ralph Loewenthal on fri 7 nov 97

Here is the formula I got from Don Jung again. Hope this
helps Ralph in PE SA.

The kiln wash that we now use is a combination of two recipes that
originated from Clayarters. One from Tom Buck...many thanks and the
other passed down through many emails through Marilyn for Robert Tetu's
kiln wash. These recipes are as follows:

Robert Tetu's Kiln Wash:

50 gm Alumina Hydrate
25 gm EPK
25 gm Silica

Tom Buck's Kiln Wash:

Alumina hydrate 32
EPK 35
Kyanite (35 mesh) 17
Silica Sand 16

Combo Kiln Wash:

Alumina hydrate 40
EPK 30
Kyanite (35 mesh) 8
Silica 22

Robert Tetu's kiln wash is excellent; very smooth, lasts a long time and
is likely what a really good commercial kiln wash is like. Only one
problem, stays on so well that glaze drips and fine spray was tough to
Tom Buck's kiln wash is also excellent, but is very coarse and rough
with Silica Sand and Kyanite granules. This I found extremely good for
removing glaze drips and glaze 'spray' (cobalt glazes). It seemed a bit
too coarse we tried a combination of the two. Well, it's
working out quite well. Holds on great but can be rubbed easily with a
silicon carbide brick to remove glaze bits. It also fills in any
irregularities and the rubbing action of the brick gets it nice and
even. Happy to say that I haven't had to chisel or grind the shelves
anymore. Haven't had any flaking or peeling, so we're just re-applying
over rubbed thin or exposed areas. By the way, don't forget to rub and
clean the underside of the shelves as dirty posts transfer bits to the
underside which in another firing will fall into some pots. Yeah, I'll
get around to cleaning the posts one day too...

Don Jung
Kensington Pottery
Vancouver BC Canada