Eleanor on sat 17 apr 10
What makes this glaze runny?
HONEY-- ^6 ox.
GERSTLEY BORATE-14
SPODUMENE-30
EPK-5
DOLOMITE-7
TALC-13
FLINT-20
RUTILE-6
BENTONITE-2
I don't know the source--the recipe was given to me by a potter I met
at a craft sale. It's all over the internet.
The numbers don't add up to 100 but it works, producing a smooth, pale
beige glaze with no pinholes, crazing, etc. It needs to be put on
fairly thick except near the bottom of the pot---too thick at the
bottom and it will run off. Glazes applied at the top of the pot will
run, beautifully.
I am glaze chemistry-challenged but I won't buy ready-made glazes (I'm
a snob?-- I don't buy cake mixes either). I mix all my glazes and am
grateful for the wonderful recipes in books (M^6G especially), on the
internet and on Clayart.
Thanks in Advance.
Eleanor Kohler
Centerport, NY
Sumi von Dassow on sat 17 apr 10
Eleanor
That's an awful lot of spodumene, which is a feldspar that is high in
lithium.
> What makes this glaze runny?
>
> HONEY-- ^6 ox.
>
> GERSTLEY BORATE-14
> SPODUMENE-30
> EPK-5
> DOLOMITE-7
> TALC-13
> FLINT-20
> RUTILE-6
> BENTONITE-2
>
> I don't know the source--the recipe was given to me by a potter I met
> at a craft sale. It's all over the internet.
>
> The numbers don't add up to 100 but it works, producing a smooth, pale
> beige glaze with no pinholes, crazing, etc. It needs to be put on
> fairly thick except near the bottom of the pot---too thick at the
> bottom and it will run off. Glazes applied at the top of the pot will
> run, beautifully.
>
> I am glaze chemistry-challenged but I won't buy ready-made glazes (I'm
> a snob?-- I don't buy cake mixes either). I mix all my glazes and am
> grateful for the wonderful recipes in books (M^6G especially), on the
> internet and on Clayart.
>
> Thanks in Advance.
>
> Eleanor Kohler
> Centerport, NY
>
>
--
Sumi von Dassow
www.herwheel.com
sumi@herwheel.com
Ron Roy on sat 17 apr 10
Hi Eleanor,
I don't know why it's running so much - but the expansion is dangerously lo=
w.
I have raised it and added some alumina to slow down the running.
Revised by Ron Roy April/10
14.00 GERS BORATE 9/97
9.50 AUSI SPOD
29.50 CUSTER SPAR
10.00 EPK
6.50 DOLOMITE
12.50 TALC
18.00 SILICA
6.00 RUTIL
2.00 BENTONITE
Total - 108.0
0.32* CaO
0.00 MnO2
0.07* Li2O
0.43* MgO
0.10* K2O
0.08* Na2O
0.02 Fe2O3
0.21 TiO2
0.17 B2O3
0.36 Al2O3
2.95 SiO2
0.00 P2O5
Si:Al: 8.29
SiB:Al: 8.76
Thermal Expansion: 415.91
Formula Weight: 295.88
Let me know if it needs more work.
RR
Quoting Eleanor :
> What makes this glaze runny?
>
> HONEY-- ^6 ox.
>
> GERSTLEY BORATE-14
> SPODUMENE-30
> EPK-5
> DOLOMITE-7
> TALC-13
> FLINT-20
> RUTILE-6
> BENTONITE-2
>
> I don't know the source--the recipe was given to me by a potter I met
> at a craft sale. It's all over the internet.
>
> The numbers don't add up to 100 but it works, producing a smooth, pale
> beige glaze with no pinholes, crazing, etc. It needs to be put on
> fairly thick except near the bottom of the pot---too thick at the
> bottom and it will run off. Glazes applied at the top of the pot will
> run, beautifully.
>
> I am glaze chemistry-challenged but I won't buy ready-made glazes (I'm
> a snob?-- I don't buy cake mixes either). I mix all my glazes and am
> grateful for the wonderful recipes in books (M^6G especially), on the
> internet and on Clayart.
>
> Thanks in Advance.
>
> Eleanor Kohler
> Centerport, NY
>
ivor & olive lewis on sun 18 apr 10
Dear Eleanor
"What makes this glaze runny?" Interesting question !
High Fluidity, Also called Low Viscosity, of a Glaze Bach is usually, thoug=
h
not necessarily, determined by four factors
1 Maturity temperature. Cone 6 may be high for this batch recipe.
2 Excessive proportions of compounds containing Group 1 Alkali metal
oxides; Lithium as Li2O, Potassium as K2O, Sodium as Na2O.
3 Appreciable amounts of substances rich in Boric Oxide
4 Interaction between the clay body on which the glaze is placed and
ingredients in the glaze batch.
Regards,
Ivor Lewis,
Redhill,
South Australia
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