Patricia Brown on sun 16 oct 05
Snail;
I'm using the stoneware clay because it's what I could get my hands on at
the time. After this first batch, I hope to fire the rest of it high fire
or get a low fire clay. I have gotten an old electric kiln that has not
been fired in over 15 years but looks to be in fairly good shape. I will do
a bisque firing in it next week then a low fire glaze. If the kiln is in
good working order for that, I'll try a cone 6 glaze which will match my
clay. It's a Knight kiln and was supposed to be able to reach cone 10 when
new.
The burnished pot was an experiment. Now my husband wants it as is, so I
will not be firing it at all or will follow your suggestion of 012-010 if I
want to do a kiln full of burnished pots.
Some crazing will be OK with me for this first firing as I'm testing with
everything: the clay, the glaze and the kiln.
Patricia
You can certainly underfire a stoneware clay to
earthewnware temperatures, but glazes will tend
to craze on it. They might craze a bit on actual
earthenware clay, but it will be much worse on
an underfired body. It's up to you whether crazing
will be a big problem. Also, an underfired
stoneware will be more fragile than an earthenware
clay fired to the same temperature.
What you are suggesting will work, but not as well
as using an earthenware clay. Are you using the
stoneware clay because it's all you can get at the
moment, or are you planning to fire most of it to
high-fire temps and this pot just an experiment?
If you are going to make a habit of low-fire glazes,
I'd suggest switching to a low-fire clay.
Bisquing to ^04 is fine in either case, though.
It's a popular choice for bisquing both stoneware
and earthenware.
Why are you burnishing first, though? The effect will
mostly be lost at ^04, even if you weren't going to
cover it with glaze. (Burnishing stays shiniest at
about ^012-^010; above that, it gets progressively
dulled.) Not only will glaze totally hide whatever
burnishing survives the ^04 bisque, but it will
actually make it slightly more difficult to glaze.
(The super-smooth surface, even though it won't be
shiny any more, can make the glaze tend to crack off
during pre-firing handling.) Or was the burnishing
part of a previous plan for the piece before you
decided to glaze it?
The glaze will adhere, but handle with care when
loading the kiln.
-Snail
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