Craig Clark on thu 31 oct 02
Tony, I haven't done any quenching for a number of years and am able to
obtain metallic lusters. This is a function of the glaze that I use, the
temperature to which the pot is fired and the speed with which I get the
piece into the post firing reduction chamber (garbage can.) I then let the
piece, one per can or maybe a feww if they are small, cool in the can until
I am able to handle them with bare hands or thin gloves. THis usually takes
about thirty minutes or so for moderate sized pieces.
As far as "functional" glazes go in the raku firing process I believe
that this idea is ill advised at best. THe average raku glaze can't even
stand up to the rigor of a humid atmosphere over the long haul. They are
photo reactive even when sealed. They are designed to CRAZE thereby exposing
bare, unvetrified clay beneath them. DO NOT USE A RAKU FIRED VESSEL for
functional purposes, if by funcitonal you mean to be used as a vessel that
contains food which will then be consumed.
If you really want the definitive skinny on what happens to raku glazes
check out the article written by Tom Buck several years back titled "Now you
see them, Now you don't." I believe that you may either access his websight
or look at digital fire. He is an expert! Trust what the man has to say.
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
----- Original Message -----
From: Leland G. Hall
To:
Sent: Wednesday, October 30, 2002 9:28 PM
Subject: Re: functional raku glazes
> On Wed, 30 Oct 2002 21:18:32 EST, BobWicks@AOL.COM wrote:
>
> >Tony:
> >I'm not sure how much Raku you have done, but in reduction firing the
> pottery
> >must be quenched with water to retain the metallic finish, but you will
get
> >cracks in the glaze. Cracked glaze will not be functional. As far as I
> know
> >the only crack free surface would be to do an oxidation fire and allow it
> to
> >cool slowly to prevent cracking of the glaze.
> >
> >Bob Wicks, Prof. Emeritus
> >Hi. My experience indicates that it is not true that "in reduction
firing
> the pottery must be quenched with water to retain the metallic finish"
> I often obtain metallic lusters (not that Tony said he was seeking
> metallics) by slow cooling in totally oxygen free atmosphere, and often
> with little or no crazing, depending on how closely the volume of the
> reduction container matches the size of the vessle. Reduceing in the kiln
> prior to post fireing reduction helps with metallics too.
> > Leland Hall, Before The Wheel Enterprises, La Pine
>
Oregon______________________________________________________________________
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>
>
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