Neil or Julie Elver on sat 20 jul 96
Hello clayart people!
At the last NCECA conference, I had the opportunity to see a tile demo by an
artist
(sorry, I can't recall his name) who used an oil based resist called C-30. He
applied
this resist with a worm blower ( it is used by fishermen to blow up worms so
they
float) to get super fine lines. I've called the suppliers that I'm familiar
with and
they've never heard of C-30 resist. Does anybody out there know where to get
this
stuff?
Also-- on the subject of barium. Does any body know how this is most
hazardous to
potters? Is it usually breathed in, injested, or aborbed into the skin? Or
possibly
all three? Also, one thing I've always wondered--how do people undergoing
some
medical tests swallow radioactive barium and come away with no health
concerns as a
result?
Thanks
Julie Elver
Charles Williams on sun 21 jul 96
Sorry, I don't know what C-30 resiet is either.
Concerning barium : Barium sulfate, used in medical x-ray exams as a contrast
agent, is an insoluble, inert, non-radioactive substance. The x-rays are
produced by a fluoroscope or standard x-ray tube and the barium sulfate is
more dense than the other tissues in the body and provides contrast. This
makes it possible to see organs and structures that cannot be seen otherwise.
Barium Carbonate, glaze making agent, is very soluble, highly toxic and can
be absorbed through the skin, swallowed or inhalled. The hazard facing the
potter is usually percutaneous absorbtion or inhallation (a very fine
powder). There has been a number of articles in the ceramic literature in
recent years, and not a little controversy, concerning the safety of barium
in glazes used on pieces designed for food containing purposes. Barium, like
lead, can be leached from some glazes, usually not properly fired to
maturity, by certain foods (acid). This can be above the limits set by the
FDA and result in fines, etc. if this is found to be the case. Most, I think,
recommend not using barium carbonate glazes on any but decorative pieces.
Some recommend not using barium carbonate at all. If used in glaze making,
one most certainly should practice good safety and wear plastic gloves and a
proper dust mask! Care should also be taken not to spill the material in your
studio -----> toxic dust!
I personally use barium carbonate but I am looking into substituting
Strontium Carbonate. I understand this works almost as well as barium in
achieving certain colors and surfaces.
Go To Pot, with a smile on your face!
Charles Williams
Cathy Nelson Hartman on sun 21 jul 96
In response to Julie Elver's question about Barium ingestion:
My wife is a government documents librarian, and she suggested the
following:
1)Find your local federal depository library (find out from
local public library or at this web site
http://www.access.gpo.gov
In our town it is the Univ. of North Texas college library.)
2)When there, ask to see the "toxic release inventory" which
will be on CD-ROM. This will explain how various chemicals can harm you,
how they get inside you, and lots of other info.
In regard to the question about ingesting radioactive barium, I know if
you have to have stomach x-rays, ie for ulcers, you drink barium sulfate,
which is insoluble and therefore not harmful, as opposed to soluble
barium carbonate which is harmful. Solubility is the trick there.
Good luck!
Walter Hartman
Ron Roy on mon 22 jul 96
Re the barium questions - by breathing and injestion or cuts in the skin.
The Barium used by doctors is a different form and is not soluble but would
present the same potential hazards in a glaze.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
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