mudduck on tue 21 dec 10
I've been trying a glaze that was in clay times a while back called =3D
Millring Green. I fire it in a down draft gas kiln to a soft cone 10 in =3D
light reduction. The problem with the glaze is it keeps going more matt =3D
black than green. When it's green it looks great but when it's black it =3D
looks bad. I thought maybe that I was applying it too thick but when I =3D
thinned the glaze down and tried that it looked just as bad because the =3D
coverage was way thin.
Here's the recipe
Millring Green
whiting 31
wollastonite 4
custer feldspar 22
EPK 28
silica 8
copper carb 3
rutile 2
bentonite 2
100
I left the bentonite out just because I thought it had enough epk to =3D
keep everything in suspension OK. Surely that wouldn't be what is the =3D
cause of the green going black.
Anyone have any ideas as to what causes the black???
Gene
mudduck@mudduckpottery.net
www.mudduckpottery.net
Ron Roy on wed 22 dec 10
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Hi Gene,
This glaze is a high calcium clay matte - perhaps the problem is
related to cooling - if the results from the top of the kiln (slower
cool) are better then changing the cooling cycle may be your answer.
Testing has also revealed that EPK is not as refractory as it once was
- I can reformulate with Tile 6 or Grolleg porcelain to see if that is
the cause.
The silica is quite low in this glaze by the way - not what I would
recommend as a liner glaze - especially with the copper in it.
RR
Quoting mudduck :
> I've been trying a glaze that was in clay times a while back called
> Millring Green. I fire it in a down draft gas kiln to a soft cone 10
> in light reduction. The problem with the glaze is it keeps going
> more matt black than green. When it's green it looks great but when
> it's black it looks bad. I thought maybe that I was applying it too
> thick but when I thinned the glaze down and tried that it looked
> just as bad because the coverage was way thin.
>
> Here's the recipe
>
> Millring Green
>
> whiting 31
> wollastonite 4
> custer feldspar 22
> EPK 28
> silica 8
>
> copper carb 3
> rutile 2
> bentonite 2
> 100
>
> I left the bentonite out just because I thought it had enough epk to
> keep everything in suspension OK. Surely that wouldn't be what is
> the cause of the green going black.
>
>
> Anyone have any ideas as to what causes the black???
>
>
> Gene
> mudduck@mudduckpottery.net
> www.mudduckpottery.net
>
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