leinweber on fri 5 jul 96
In our ceramics class, we are experimenting with taking the barium out of our
glazes--mixing small samples and testing them to see what happens. will have sa
out of the kiln on monday. we will also be experimenting with making substitut
the barium, and would appreciate any suggestions about different materials to us
barium today, what will be next?
thanks, sandra l.
Ron Roy on sun 7 jul 96
>----------------------------Original message----------------------------
>In our ceramics class, we are experimenting with taking the barium out of our
>glazes--mixing small samples and testing them to see what happens. will
>have sa
>out of the kiln on monday. we will also be experimenting with making
>substitut
>the barium, and would appreciate any suggestions about different materials
>to us
>barium today, what will be next?
>thanks, sandra l.
For Sandra,
I think we know what materials have risk associated with them. What we
don't know is how much risk. We also know which materials are safe under
specific conditions.
There is much written about substitution of oxides in many tests -
Suggested substitutes for Barium are strontium, calcium and zinc and
perhaps even magnesium - the middle and high temperature fluxes. The best
way to find out how much to substitute is with glaze calculation.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Tony Hansen on wed 10 jul 96
I know this barium thing has been discussed before but I didn't get to
put in my 2 cents worth. Maybe barium is safe under the right
circumstances (i.e. in a ceramic factory where technical people are
available). However most potters and educators are not glaze
technicians. I have seen 30% barium in underfired mattes, I've seen tons
of cone 10 glazes severely lacking in SiO2 and alumina. These are what
are being used by potters and education, these are what you find in
textbooks. I've seen the vinegar test turn a bright blue bowl snow
white. The vinegar soaking test is great because it tells us if a glaze
is balanced and functional. If the glaze fails this test it should
definitely not contain barium.
If you know how to make barium safe, then use it; but don't tell anyone
and don't say anything that even implies that non-technical people
should be using it. We buy barium by the carload along with a hundred
other ceramic chemicals. Barium is the only one with a big skull and
cross bones on the bag and it comes with safety data sheets that say
"look out". The empty barium bags are classified as toxic waste. You can
eat kaolin, dolomite, flint, whiting, talc, feldspar, and lots of other
ceramic mineral powders, but don't touch barium. I'm not a technical
person on this so I have to go on common sense.
--
-----------------------------ooO-(_)-Ooo---------------------------
Tony Hansen, IMC, 134 UPLAND DRIVE, Medicine Hat, Alberta
T1A 3N7 Canada Phone:403-527-2826 FAX:527-7441 BBS:527-6074
email: thansen@mlc.awinc.com web: http://digitalfire.com/imc.html
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