Dupre Mr Marcy M on fri 6 jun 03
-----------------------------<Cone Six - 14 Celadon
Range: 5-7
Firing type: Oxidation
Glaze type: Celadon
Color: Green
Surface: Semi-gloss
Transparency: Translucent
Visual texture: Mottled
Date: 01/30/2002
Wollastonite 20.00 20.00%
Calcined china clay 10.00 10.00%
Silica 10.00 10.00%
Gerstley borate 10.00 10.00%
Soda feldspar 50.00 50.00%
-------- -------
100.00 100.00%
Copper carbonate 0.50 0.50%
Black Stain 0.20 0.20
-----------------------------<
Jonathan,
Did I send this glaze to you? If so, check your materials. I used calcined
EPK, Gillespie borate, and Minspar (for the soda spar). As I recently
learned, Kona F4 isn't really available any more. A direct substitute is
Minspar.
As I write this, my kiln is cooling a load of porcelain communion sets
glazed with this ^6 "celadon." (I put "celadon" in quotes so as not to
offend the purist out there, waiting to pounce! :o)) The test tiles I did
are a beautiful Dolphin Grey-Green. Eager to see the pots.
Word of caution: Sieve in an 80-mesh three times, very carefully. The
slurry should look like really thick cream. I dip and hold for a
three-second count, then allow to drip. Dry thoroughly or candle for a
couple for hours before kicking the "ON" switch.
Get muddy,
Tig
Tom Buck on mon 9 jun 03
Jonathan:
at first blush, your Cone 6 Celadon mix should work ok, and not
leach anything serious. But I will do glzcalc and give an opinion.
as for Gerstley Borate (GB) vs Frits: currently Laguna is peddling
its 2-3000 ton lode which may run out in a year or so. Meanwhile at least
two replacements are available, Gillespie Borate and Boraq, that offer GB
properties of the 1980s.
it boils down to price: Laguna through its dealers is selling
mineral GB at 35-40 cents (US) per pound when 50-lb bag is bought, say $20
a bag locally to you. Gillespie Borate runs the same in New Jersey; Boraq
runs about $25 US in Alberta.
the borate frits are $60 - 100 (US) per 50-lb bag.
If you are doing Raku, an 80/20 mix will be 2-3 times more expensive
with a frit.
as an aside, I suggest you follow a simple procedure when weighing
out a recipe batch, and make up this table:
List the recipe with percentage of item; name of item/ingredient; amount
actually weighed (say 20 times recipe); check box; cost per unit (lb or
kg); total cost of ingedient/item in batch.
then summarize all at bottom, and attach this sheet to the bucket (side or
lid). Hence, you will be always reminded how expensive is this mix, and
your will have a copy of the mix to use as guide for the next weighing.
Good pots. Peace. Tom B.
Tom Buck ) -- primary address.
"alias" or secondary address. tel: 905-389-2339 (westend Lake Ontario, province of Ontario,
Canada).
mailing address: 373 East 43rd Street, Hamilton ON L8T 3E1 Canada
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