arturo m devitalis on sun 14 feb 99
It was suggested to me after my supplier changed their source for
purchashing grog
that I should raise my bisque temp from 06 to 04 to avoid glaze pinholes
in the cone 10-11 glaze (reduction) firing. In my mind all the clay will
outgas in glaze firing long before the glazes begin to melt - so what
good does raising the bisque temp accomplish? I am obviously missing
something...what is it?
Arturo DeVitalis
devpot@juno.com
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Ron Roy on fri 19 feb 99
Hi Arturo,
There is not much point in raising the bisque temp from 06 to 04 if that is
the problem you are trying to cure. It's part of the cure for dunting
though because it makes the ware a bit stronger.
Firing slow enough and with excess oxygen between 700C and 900C will give a
"clean" bisque and help to avoid certain types of pinholes (blisters) over
clays with more than a little iron oxide. The sure sign that it is this
type of problem (overfired clay due to reduced iron) - refiring makes it
worse.
Just slow down the bisque firing and make absolutely sure you are in strict
oxidation.
RR
>----------------------------Original message----------------------------
>It was suggested to me after my supplier changed their source for
>purchashing grog
>that I should raise my bisque temp from 06 to 04 to avoid glaze pinholes
>in the cone 10-11 glaze (reduction) firing. In my mind all the clay will
>outgas in glaze firing long before the glazes begin to melt - so what
>good does raising the bisque temp accomplish? I am obviously missing
>something...what is it?
>
>Arturo DeVitalis
>devpot@juno.com
>
>___________________________________________________________________
>You don't need to buy Internet access to use free Internet e-mail.
>Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
>or call Juno at (800) 654-JUNO [654-5866]
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
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