Jada Ahern on sat 12 feb 00
------------------
Hi..
I was making a Hi-Fire Glaze this past week.. and being the bubble head of =
the
day, unintentionally substituted Copper Carbonate for Cobalt Carbonate.
What follows is the =22REAL=22 formula..
LAPIS BLUE
Cone 10 Redux
Custer Spar 40=25
Whiting 25=25
Cornwall 20=25
EPK 15=25
Cobalt Carb 2=25
Bentonite 2=25
This glaze tested beautifully... in the small batch. (beautiful matte =
blue)
I now have a beautiful 10,000 gr batch of this made with Copper Carbonate. =
I
would consider it a barf matte pea green with dark plum accents and crazing
through-out. This is NOT what I was looking for. I would appreciate and =
advice
just short of adding it to the mystery glaze bucket.
Thanks in advance=21
Jada
in sunny TUCSON, Arizona
Manager-Hummingbird House Studios
hummingbirdhouse.com
June Perry on sat 12 feb 00
Jada, just add some cobalt to the "Barf green". I have a lovely blue glaze
that has cobalt and copper and rutile as the colorants.
You can try to add 1% cobalt to start and add more if you want a more intense
blue.
Good luck
June
Paul Lewing on sun 13 feb 00
Hi, Jada.
Now here's a problem all of us have had to face at one time or another.
A little temporary early Alzheimer's while mixing and Voila! A Whole New
Color!
Well, you can't take the copper out so you have to work with it. Either
modify it or overpower it. This will take some testing, but don't throw
it out- you can always do something with it.
First, since you now have wet glaze instead of dry powders, your tests
will have to be a volume of wet glaze with weight additions of
colorants. For ease of conversion to a big batch, I'd suggest 100 cc's,
which is 1/10 of a liter as a test batch size. Then I'd test additions
of 1, 2, 4, and 6 grams (these are all done in one 100cc batch, testing
after each successive addition), and I'd test using cobalt carbonate,
iron oxide, rutile, manganese dioxide, chrome oxide, zircopax, and maybe
even additional copper carbonate. If you have a bucket of scrap glaze
around that makes a dark green, I'd try mixing this with the scrap
half-and-half. Or if you have a white glaze around, try mixing this
with that. After that round of testing, try adding some of the tests
together for more complex colors. If all else fails, add 1% each cobalt
carb and chrome oxide, plus 2% each of iron oxide and manganese dioxide.
You'll get black. And if the crazing persists, run the same test series
with additions of silica. That very well might fix that.
Anyway, don't give up on it. If you do enough tests on this stuff,
eventually you'll either find something you like or use it all up.
Either way, you'll have learned a lot. Good luck.
Paul Lewing, Seattle
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