Donna Light on sat 14 jul 07
I'm getting ready to do my first firing in my New/Used kiln. I have one
question.
Is it true that you can use only Cone 1 and up glazes on Stoneware and Cone
06 and lower glazes on Earthenware?
I can't wait to fire, but I want to make sure I'm doing it right. I'm
waiting on Kiln wash before I do the first firing.
Thanks!
Donna
nanspin-AT-gmail on sun 15 jul 07
It's my understanding that you shouldn't fire your glazes any higher than
you fire your clay to bisque. For example, if you have 05/04 clay, fire it
first to 04, but pick a glaze that is 06/05 -- if you try to use a ^6 glaze
on earthenware, your clay will melt.
I don't know about using earthenware glazes on stoneware, but stoneware
glazes on earthenware is definitely a no-no! :)
Have fun!
--Nancy
On 7/14/07, Donna Light wrote:
>
> I'm getting ready to do my first firing in my New/Used kiln. I have one
> question.
>
> Is it true that you can use only Cone 1 and up glazes on Stoneware and
> Cone
> 06 and lower glazes on Earthenware?
>
> I can't wait to fire, but I want to make sure I'm doing it right. I'm
> waiting on Kiln wash before I do the first firing.
>
> Thanks!
> Donna
>
>
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claystevslat on sun 15 jul 07
Donna --
That one, simple question you asked raises quite a few
issues.
First -- Glazes are generally formulated to a fairly
narrow range of temperatures. Often they are described
as being specific to a single 'cone' temperature -- such
as cone 6 glazes, cone 04 glazes, or cone 11 glazes.
Second -- The most important thing -- but not the only thing --
about them is that they are designed to fully melt (vitrify)
at that temperature, but to remain physically attached to
a pot with vertical surfaces (that is, not to run off the
side of the pot and make a mess on the shelf).
Third -- clays are formulated to specific cones (or ranges)just
as glazes are. Stoneware and porcelain fired to the correct
temperature may be equally vitrified and resistant to
water absorbtion and so on. But the definitions of stoneware,
porcelain, and earthenware are not as specific as you might
think. Some people will say anything that's white and fires
to cone 10 is porcelain, others will say that it's got to be
translucent when thin to be porcelain, some will argue that
a white clay that's translucent at cone 6 is not a porcelain
because that's not the right firing temp.
Earthenware is generally defined as a porous body (5% or more
absorbtion) that must be glazed, if it is necessary for it to be
sealed.* But some people will add the additional specification
that earthenware is fired to under cone 4. And some stonewares
I've worked with are porous even at cone 6 or cone 10.
So all these definitions are a little vage.
Fourth -- This does not mean that there is no consequence to
the glaze of different glay bodies. I have bodies that do
well over some stoneware but not some porcelain, or over
some porcelain but not others, even if the clays are 'rated'
to the same cone.
So my advice to you is to avoid concerning yourself with the
words 'earthenware' and 'stoneware' and concentrate on the
cones. Cones measure heatwork, and are the accepted standard
(with known definitions) for firing. Find a kind of work you
like, select a clay in that range and a glaze that matures at the
same cone. Then fire to that cone. Finally, test your results.
If it 'works' well at the cone you fired to, you're OK. If not,
try another glaze or twenty ... until you like your results.
-- Steve Slatin
*Definition derived from The Potter's Dictionary -- yes, I'm
again using the Hamers as hammers.
--- In clayart@yahoogroups.com, Donna Light wrote:
>
> I'm getting ready to do my first firing in my New/Used kiln. I
have one
> question.
>
> Is it true that you can use only Cone 1 and up glazes on Stoneware
and Cone
> 06 and lower glazes on Earthenware?
>
> I can't wait to fire, but I want to make sure I'm doing it right.
I'm
> waiting on Kiln wash before I do the first firing.
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