Llewellyn Kouba on fri 3 mar 00
Readers,
My instructor at school used to or still does an 08 body reduction. I fired
a 45 cu ft. downdraugh/reduction kiln. I am wondering how I might handle a
'body' reduction for stoneware and porcelain? would it be and atmosphere
with a lot of oxygen, but then that doesn't sound like a body reduction? I
have also realize there are some pitfall in too early a reduction in
trapping gases in the clay before they have had a chance to release and may
cause bloating. I have experimented with body reductions but wonder how
necessary they are...or is is the benefit maybe just that it is a 'slow'
time and gives the clay more time to cook itself out? any helps would be
welcomed
Llewellyn /where I hope kiln day will be before next fryday!
ABBEY POTTERY
http://www.assumptionabbey.com/Pottery
Ron Roy on mon 6 mar 00
Hi Llewellyn,
I start my reduction anywhere from 850C (come 012) up to 1050C (cone 04)
depending on the glazes - if you don't start before 1100C the body is too
tight and will not get properly reduced all the way through.
If the bisque has been fired properly the sulphure and carbon will be gone
so it is not a comcern during the glaze fire. If you are single firing it
will be a problem unless you take care to get the organics out - this has
to do with speed and having free oxygen available.
If you don't reduce the body before the glaze seals over you will not get
the same results - the glazes will look different. I think it is best to
stay in light reduction all the way up. You have to think of all glazes as
sealing over at differnt temperatures. Shino glazes with a lot of soda ash
in them are going to seal over faster simply because sodium - which is
consentrated on the surface of the glaze - is a heavy duty flux starting at
850C - that is cone 012.
If there is boron present it starts fluxing even before that - imagine how
useful it would be if we all understood at what temperature the oxides we
use starting doing their job.
RR
>----------------------------Original message----------------------------
>Readers,
>
>My instructor at school used to or still does an 08 body reduction. I fired
>a 45 cu ft. downdraugh/reduction kiln. I am wondering how I might handle a
>'body' reduction for stoneware and porcelain? would it be and atmosphere
>with a lot of oxygen, but then that doesn't sound like a body reduction? I
>have also realize there are some pitfall in too early a reduction in
>trapping gases in the clay before they have had a chance to release and may
>cause bloating. I have experimented with body reductions but wonder how
>necessary they are...or is is the benefit maybe just that it is a 'slow'
>time and gives the clay more time to cook itself out? any helps would be
>welcomed
>
>Llewellyn /where I hope kiln day will be before next fryday!
>ABBEY POTTERY
>http://www.assumptionabbey.com/Pottery
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
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