John Hesselberth on tue 17 nov 98
Ralph, Barium sulfate is not toxic only because it is about the only form
of barium that is not noticeably soluble in body fluids. That is why you
get to drink a quart of what I call a barium milkshake when you have your
small intestine Xrayed (it gives good contrast on the Xray and allows the
radiologist to sort out the small intestine from all that other stuff).
Even then they advise you to drink lots of water to flush it all out
quickly. However in a glaze it quickly turns into barium oxide when
heated in your kiln. In the end product (your glazed pot) it is no
different than using barium carbonate or barium oxide. In glaze, barium
is barium!
Fay & Ralph Loewenthal wrote:
>----------------------------Original message----------------------------
>Right on Monona. I sent a Clayarter a couple of Barium
>glaze recipies off the list with strong cautionary statements
>about the toxicity of Barium Carbonate.
>I remember using a glaze with a high percentage of BaCO3
>(40%) on a bowl. My wife put in potato salad made with
>mayonaise and the glaze discoloured. That is when I
>discovered that what I was led to believe was incorrect. I
>was told that the glaze was toxic while in the raw state, but
>was OK once fired. Another myth blown out of the water.
>I have been experimenting with Barytes (Barium Sulfate)
>to try and get the same colours, but no luck so far. Barytes
>is the gunk they feed you when you have a Barium Meal to
>find out if you have ulcers or not. I assume it is not toxic.
>We have had this discussion before about Barium,
>Manganese and other toxic substances. I have kilobytes of
>stored threads on this subject. It all adds up to practising
>caution rather than being blase about toxic substances and
>possible effects. As Monona pointed out there are tests
>being conducted, once there is sufficient data only then can
>we be certain how to handle the various toxicities. Until
>then I would rather be a live, healthy and happy potter, who
>errs to the side of caution, than somebody who is suffering
>from various ailments not knowing what has caused it. I
>already have allergic asthma caused by being forced into
>passive smoking, I certainly do not need any other
>problems.
>Karl, I feel that your outburst shows more hysteria than the
>cautionary statements by other potters. For the most part,
>we are all learning and do not have the knowledge and
>expertise that you and other proffesionals have. We do not
>instintively know what is toxic and what is not. It helps that
>there are pottters and others who are prepared to impart
>their knowledge to the rest of us who just do not have the
>experience. Even if the knowledge imparted is not based on
>sceintific facts, it is still better to be warned than to carry on
>blindly regardless of the consequences.
>Here is a story to emphasize this point even more. I saw
>some pottery, functional ware, being sold at an art store
>in Jerusalem recently. The glaze I recognized as one that I
>make and sell, with strong warnings to be used only on
>decorative ware. This glaze has 40% Barium Carbonate in
>it. I pointed out to the proprietor that that glaze was toxic
>and should not be on the inside of wine goblets, salad
>bowls, etc. She showed me a note, written in Hebrew, from
>the potter, stating that glaze was not toxic. Obviously the
>potter was under the same misconception that I was and
>did not realise that the Barium Carbonate leaches out. I
>unfortunately did not get the chance to contact her and tell
>her. That is what happens when potters are not informed.
>The buying public is put at risk. G_D forbid that even one
>customer should die or even become seriously ill from such
>ware then the whole industry is brought into disrepute. It is
>at those times that government departments step in and
>over react. The whole industry can become over regulated
>because of just one such incident. Nobody would like to
>have to submit samples from every firing to test
>laboratories, before being allowed to sell their wares.
>Just another perspective that should be kept in mind. Ralph
>in PE SA
John Hesselberth
Frog Pond Pottery
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"The whole aim of practical politics is to keep the populace alarmed, and
hence clamorous to be led to safety, by menacing it with an endless
series of hobgoblins, all of them imaginary." H.L. Mencken, 1925
| |
|
