D Beverlin on fri 15 aug 03
I am thinking of rebuilding the kiln because my last few glaze fires have
been awful. And the roof is pretty sad.
I have had a lot of trouble with blistering. And I mean blistering all
over. The more I refire the worse it gets. I tried soaking as per Mels
instructions on Clayart some time back. But I misread and soaked for two
hours at cone 9/10 then as I read further I realized that you meant for the
kiln to cool to 1900 then hold.
Any way the kiln roof is missing part of some bricks and I thought that I
was cooling too fast.
I am really stumped. And a little desperate as I have several orders to get
out.
So... I am posting a copy of this to clay art and hope I get some clear
answers. I would like to wait until after the rush to rebuild.
PS I am going to buy the brick K26's as I can get them for 63 cents if I
get them now. is this a good price for 2nds? They have K28's for 70 cents.
PSS I do bisque in the gas kiln and hold temp for an hour or so to burn out
the impurities. I don't close the peep hole during the bisque fire either.
Well I am rambling on.. back on my head break is over.
have a sunshine day
darlene
Ron Roy on sat 16 aug 03
Hi Darlene,
Sounds like a classic case of dirty bisque - what kind of clay are you using?
If the organics are not burnt out of the clay during the bisque they will
reduce any iron and turn it into a flux - overfiring the clay and causing
blisters - which get worse when refired.
Slow your bisque firing down - particularly from 700C to 900C and make sure
there is NO reduction and supply plenty of oxygen - to aid the burning off
of the organics.
RR
>I am thinking of rebuilding the kiln because my last few glaze fires have
>been awful. And the roof is pretty sad.
>
>I have had a lot of trouble with blistering. And I mean blistering all
>over. The more I refire the worse it gets. I tried soaking as per Mels
>instructions on Clayart some time back. But I misread and soaked for two
>hours at cone 9/10 then as I read further I realized that you meant for the
>kiln to cool to 1900 then hold.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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