Michelle Rhodes on sat 20 feb 10
Flocculation? I have a cone 6 to 8 glaze formula from years ago
(Gib Matte) that is opaque and very matte from zinc. The problem
is it has no shelf life. It turns into thick cream if I don't use it
within 24 hours and doesn't apply well. I have tried adding sodium
silicate but it doesn't help much. Perhaps I use too much or too
little, add it too soon or too late? Is there something I could
substitute for some or all of the zinc? I don't want to use barium
carbonate or rutile. What is the best way to solve this problem?
What I love about this glaze is that it picks up overglaze and
underglaze cobalt and copper oxides and stains beautifully and
intensely and has a hard, crystalline surface. I like to use it for
tiles and sculptures and the occasional functional piece. I fire
this in my electric kiln to cone 7 on Tucker white sculpture/raku .
Is it typical for a glaze with this much zinc in it to have this
problem? Here is the formula:
Neph Sy 56.8
Whiting 12.2
Zn Ox 10.8
Georgia Kaolin 18.6
Flint 1.6
Michelle Rhodes, Gardiner NY
Wyndham Dennison on mon 22 feb 10
>
> Flocculation? I have a cone 6 to 8 glaze formula from years ago
> (Gib Matte) that is opaque and very matte from zinc. The problem
> is it has no shelf life. It turns into thick cream if I don't use it
> within 24 hours and doesn't apply well.
Excessively flocculating zinc glaze in this case might be remedied by calci=
ning half the Georgia kaolin or buying some Glomax which is calcined kaolin=
and using calcined zinc for the regular zinc. If this is still an issue, i=
ncrease the ratio of glomax to to Georgia kaolin 60/40 or 70/30 but keep th=
e same total percentage of clay in the glaze.Hope this helps. Wyndham
Mark and Sylvia Mondloch on mon 22 feb 10
Michelle,
I use a similar recipe with 16% Zinc Oxide and it does pudding up when it
sits. When I'm ready to use it, I beat it with a drill mixer and then add
Darvan 7 (carefully or it will hardpan). I'd be curious to hear how the
macro-crystalline glazers deal with zinc oxide.
My first post after about a 5 year break,
Sylvia
Sylvia and Mark Mondloch
Silver Creek Pottery & Forge
mondloch@silvercreekpottery.com
www.silvercreekpottery.com
It turns into thick cream if I don't use it
> within 24 hours and doesn't apply well. .
>
> Is it typical for a glaze with this much zinc in it to have this
> problem? Here is the formula:
>
> Neph Sy 56.8
> Whiting 12.2
> Zn Ox 10.8
> Georgia Kaolin 18.6
> Flint 1.6
>
> Michelle Rhodes, Gardiner NY
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