Gordon on sat 24 may 97
Dear Guru- I have just "rediscoverd" a glaze that I had used a few years
ago and I was about to happily mix it up again I came across the dreaded
"BariumCarbonate". What can I sub for this and get the same results?
^7 Oxidation glaze from Tony W.T. Yeh (3/95 CM)
2.86 Barium Carbonate
ADD.95 Nickel Oxide
7.62 Red Iron Oxide
Thank you thank you thank you oh great guru!
"If things seem under control you are not going fast enough"
pjomjp[ on sun 25 may 97
>>"BariumCarbonate". What can I sub for this and get the same results?<<
You could probably leave it out and not notice it was gone. But why
remove it? Paranoia? Not worth it
Mike Vatalaro on tue 27 may 97
Consider using strontium carb to sub for barim . a formula i've heard
works is multiply barium amount by 75% or 3/4 to get the amount of
strontium needed. Be sure it is FINE ground the coarse stuff is worthless.
also if its in the mid to low temp range 08--6 consider a barium fritt
Ive used Q257 from ferro for several years now .
Mike Vatalaro, Clemson U
Ron Roy on wed 28 may 97
>Dear Guru- I have just "rediscoverd" a glaze that I had used a few years
>ago and I was about to happily mix it up again I came across the dreaded
>"BariumCarbonate". What can I sub for this and get the same results?
> ^7 Oxidation glaze from Tony W.T. Yeh (3/95 CM)
>2.86 Barium Carbonate
>ADD.95 Nickel Oxide
>7.62 Red Iron Oxide
Well this is a good example of a glaze that simply does not need any BaO
for any reason I know of. My cost for Barium Carb. is five times the cost
of Calcium Carbonate I used to replace it. Perhaps some think more
expensive glazes are better.
I also notice the expansion is high and suspect it will craze on most
bodies. The Silica part of this glaze was at the lower limits for a durable
glaze so I increased that a bit and so lowered the expansion a bit at the
same time. This should be a durable glaze. The expansion is still on the
high side so I would check for crazing.
Always test a revision before you mix up a large batch - consider mixing
500 grams and weigh very carefully - balance your scale before you start.
10.5 - Talc
19.0 - Whiting
47.5 - G200 spar ( Custer will work as well)
7.5 - EPK
15.5 - Silica
1.0 - Nickel oxide
7.5 - red iron
Ratio 8.28 ( the ratio of the original is 8.07)
Evenings, call 416 439 2621
Fax, 416 438 7849
Anglersnet on wed 28 may 97
If you would prefer not to use Barium Carbonate, and omitting it isn't
satisfactory, my first suggestion would be to try increasing the Talc in
it's place. If all of the simple substitutions aren't successful, by far
the most similar replacement would be to use Strontium Carbonate.
Plfgonnago on mon 9 jun 97
You need to be aware that glazes mixed with strontium have a limited shelf
life when in a liquid state. In several weeks the strontium carbonate
breaks down into SOMETHING ELSE, and the strontium glaze that was once
beautiful will look like Something Else.
Evan Dresel on tue 10 jun 97
(OK Tony, Personally I like to see what people are refering to before I
read the reply rather than guessing at the pertinent info, but I'm happy to
try putting the cart before the horse or whatever)
Hmm, interesting. Where could the strontium go? It's a non-radioactive
element so it won't break down to anything. Strontium carbonate is less
soluble than calcium carbonate (whiting) or magnesium carbonate so I doubt
it's going into solution. I suppose it could be reprecipitating as
celestite (strontium sulfate) if you have any sulfate in the glaze, but that
seems unlikely. Maybe it is settling out more than the other suspended
solids and not getting resuspended as you stir. Still, I suspect something
else is causing your glaze to turn gross.
At 04:43 PM 6-9-97 EDT, you wrote:
>You need to be aware that glazes mixed with strontium have a limited shelf
>life when in a liquid state. In several weeks the strontium carbonate
>breaks down into SOMETHING ELSE, and the strontium glaze that was once
>beautiful will look like Something Else.