John Post on wed 25 apr 07
The thread about Fat White happened in September of 2005.
Basically I developed a fat white, Ron Roy contributed a variation of it
and I think Bill Edward's created a revision too. If you are interested
check the archives. Some of what I wrote then is reposted below.
John Post
Sterling Heights, Michigan
----------------------------------------------------------------------------------------------------------
This is a glaze I developed using Ian Currie's grid method. It's a nice
soft buttery magnesium matte glaze.
I call it Post's 244 The unity formula has .4 magnesium and .4 calcium
with another .2 of other fluxes. Thus the title 244 It is a cone 6 glaze
fired with a slow cool. It feels great on both the dark body and the
light body I have tried it on, though the dark is richer visually.
28.7 EPK 21.5 Frit 3110 16.9 Dolomite 2.9 Talc 30 Flint
0.18 Na2O .02 K2O .4 MgO .4 CaO
.41 Al2O3 .03 B2O3
3.47 SiO2
expansion is low at 61.7 x 10e-7 per degree C
Now I know that this glaze does not fall into the standard limit formula
range for a stable cone 6 glazes to use with colorants. But it is a
smooth as a baby's butt and feels great to the touch. Since I explored a
couple of Currie grids with magnesium at cone 6, I was trying to develop
a glaze that felt the softest to the touch and this one was it. If you
try this glaze with colorants, send it in to a lab to have it tested. Do
the homework if you choose to make it yours.
-----------------------------------------------------------------------------------------------------------------------------
The whole experiment with Post's 244 was to develop a buttery magnesium
matte glaze at cone 6. Stability and staying within the limits was not
the goal.
Rhodes 32 is short of silica, yet mel has been using it for years. I
have run 2 Currie grids so far using magnesium as the main flux.
It appears to me as though the buttery smooth feel is dependent on not
only the magnesium, but on the relationship between it and silica and
alumina. I will add some copper to the Post's 244 and send it in for lab
testing...just because I am curious about it. I like it just the way it
is with its smooth fat white feel. I am not worried about it leaching
anything into food, because there are not any metals in it that I am
concerned about.
The 3 different variations I tried all worked ok. My favorite studio and
classroom glaze has 24% clay in it. The high clay content of the Post's
244 is not a problem for me. I prefer glazes high in clay. Ron's and
Bill's variations worked fine. I think the application on Bill's
variation was a little thin and that may account for the clay body
showing more through his glaze. I think his idea of adding tin to his
variation will probably remedy that. Ron's variation was opaque. I still
think the original has a slightly more buttery surface than either
variation...but only marginally.
Ron Roy on thu 26 apr 07
Hi John,
I don't keep most of the glazes I work on - would you be so kind as to send
me a copy of "my" version.
If and when you do have yours tested - would you please send the results to me.
Thanks - RR
>The thread about Fat White happened in September of 2005.
>Basically I developed a fat white, Ron Roy contributed a variation of it
>and I think Bill Edward's created a revision too. If you are interested
>check the archives. Some of what I wrote then is reposted below.
>
>John Post
>Sterling Heights, Michigan
>
>---------------------------------------------------------------------------
>-------------------------------
>
>This is a glaze I developed using Ian Currie's grid method. It's a nice
>soft buttery magnesium matte glaze.
>
>I call it Post's 244 The unity formula has .4 magnesium and .4 calcium
>with another .2 of other fluxes. Thus the title 244 It is a cone 6 glaze
>fired with a slow cool. It feels great on both the dark body and the
>light body I have tried it on, though the dark is richer visually.
>
>28.7 EPK 21.5 Frit 3110 16.9 Dolomite 2.9 Talc 30 Flint
>
>0.18 Na2O .02 K2O .4 MgO .4 CaO
>
>.41 Al2O3 .03 B2O3
>
>3.47 SiO2
>
>expansion is low at 61.7 x 10e-7 per degree C
>
>Now I know that this glaze does not fall into the standard limit formula
>range for a stable cone 6 glazes to use with colorants. But it is a
>smooth as a baby's butt and feels great to the touch. Since I explored a
>couple of Currie grids with magnesium at cone 6, I was trying to develop
>a glaze that felt the softest to the touch and this one was it. If you
>try this glaze with colorants, send it in to a lab to have it tested. Do
>the homework if you choose to make it yours.
>
>---------------------------------------------------------------------------
>--------------------------------------------------
>
>The whole experiment with Post's 244 was to develop a buttery magnesium
>matte glaze at cone 6. Stability and staying within the limits was not
>the goal.
>
>Rhodes 32 is short of silica, yet mel has been using it for years. I
>have run 2 Currie grids so far using magnesium as the main flux.
>
>It appears to me as though the buttery smooth feel is dependent on not
>only the magnesium, but on the relationship between it and silica and
>alumina. I will add some copper to the Post's 244 and send it in for lab
>testing...just because I am curious about it. I like it just the way it
>is with its smooth fat white feel. I am not worried about it leaching
>anything into food, because there are not any metals in it that I am
>concerned about.
>
>The 3 different variations I tried all worked ok. My favorite studio and
>classroom glaze has 24% clay in it. The high clay content of the Post's
>244 is not a problem for me. I prefer glazes high in clay. Ron's and
>Bill's variations worked fine. I think the application on Bill's
>variation was a little thin and that may account for the clay body
>showing more through his glaze. I think his idea of adding tin to his
>variation will probably remedy that. Ron's variation was opaque. I still
>think the original has a slightly more buttery surface than either
>variation...but only marginally.
>
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>
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>
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Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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