Lee Love on tue 2 mar 10
On Tue, Mar 2, 2010 at 8:02 PM, Paul Borian wrote:
> if anyone knows of a site that explains all this in technical detail coul=
=3D
d
> you provide a link? Or even suggest a good book to read that would explai=
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n?
>
Paul, Digitalfire is a wellspring of information:
http://digitalfire.com/4sight/education/limit_formulas_and_target_formulas_=
=3D
206.html
--=3D20
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Paul Borian on wed 3 mar 10
some of my glazes have silica and alumina levels that are below the limit
formulas for cone 10 and these glazes tend to be more problematic than the
ones that fall within the limits. In particular, they are prone to
blistering especially if fired too fast or in the hottest part of the kiln.
I am currently in the process of raising the silica and alumina levels to
try and minimize this problem but it will have to be a gradual thing
because i know they will not look the same, and i have to be careful about
making major changes to my wholesale product line.
is there anyone out there that could explain, in fairly technical terms,
just WHY a glaze that falls below the limits for Silica and alumina at a
given cone is more likely to come out with flaws? I know the simple answer
is "because it is overfired" but i am trying to get a better understanding
of what is actually going on with the glazes.
Also, the second part to this question is, suppose i find it impossible to
get the same look by raising BOTH silica and alumina but i can raise one or
the other with good results. With the main goal of eliminating blisters and
such, which of these two is most important to have within the limits? In
other words, would a glaze that is too low in silica be more likely to
blister than a glaze that is too low in alumina? or would it be the
opposite?
if anyone knows of a site that explains all this in technical detail could
you provide a link? Or even suggest a good book to read that would explain?
any replies greatly appreciated as always!
thanks,
Paul
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