Craig Martell on fri 21 nov 97
Hi:
I adjusted the blacksmith glaze and brought the silica up to a little above
the lower limit and thought I should post it to the list in case someone
would like to try it. I'm sending another one too, Larry's Black, that is a
very durable glaze and has much more silica than Blacksmith. Whether or not
anyone uses these on funcional pots is, of course, up to the maker. I'd
have these tested for leaching though, just to be sure. If you use them on
the outsides of pots and on surfaces that don't see a lot of action with
food, they shouldn't cause any problems. In the raw state, care should be
used for the obvious reasons. You might also try lowering the percentages
of colorants, one at a time, to see if they can be added in smaller amounts
thereby saving some dough and lessening the risk of leaching etc. I plan to
test both versions of the blacksmith glaze because I'm curious about the
potential differences.
Blacksmith (adjusted)cone 10 R
CUSTER FELDSPAR 46.96 CaO 0.42*
DOLOMITE 15.65 MgO 0.31*
EPK KAOLIN 26.09 K2O 0.19*
WHITING 2.61 Na2O 0.08*
SILICA 8.70 Fe2O3 0.01
======== TiO2 0.00
100.00 Al2O3 0.64
SiO2 3.23
RIO 4.0
Cobalt Carb 3.0
Manganese Diox 2.0
Chrome Ox 1.0
Cost/kg 0.02
Si:Al 5.06
SiB:Al 5.06
Expan 7.09
Larry's Black cone 10 Ox or Red
CUSTER FELDSPAR 42.00 BaO 0.05*
WHITING 13.00 CaO 0.63*
EPK KAOLIN 8.00 MgO 0.01*
BARIUM CARBONATE 2.00 K2O 0.22*
SILICA 20.00 Na2O 0.10*
BENTONITE 2.00 Fe2O3 0.01
======== TiO2 0.00
87.00 Al2O3 0.50
SiO2 4.28
Use the same colorants and percentages as Blacksmith.
Cost/kg 0.06
Si:Al 8.62
SiB:Al 8.62
Expan 7.31
Craig Martell-Oregon
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