Katheryn Corbin on thu 20 nov 97
Dear Forum...
How stable is barium when it is fired to cone 6?
Is it safe to use on cups?
I have just fired some porcelain cups to cone 6 and wondering if they are
stable for use.
I also used a wash of Mg.,Cobalt,Cu. for lines...is it stable at 6 if it
goes to the rim?
I have used BaCO3 and have thought the danger was in the raw state. Once
fired, when is there danger of leeching with use? At what cone is the
chemical released?
There has been much discussion on use of barium frit. Is this for safety
in the studio or for the final product?
The functional is scary.
Katheryn
http://www.axisnet.net/~corbin
geneviev@southwind.net on fri 21 nov 97
Katheryn,
Barium used in a glaze intended to be functional should have no more than =
5=25
barium. If the glaze contains more, it will leach. Barium is more toxic to
your body, in the fired state ( as in a glaze ) than it is in the raw state.
Your body can absorb the barium when it is leached out into food. As a raw
materials it is not absorbed easily, that is why they use it for barium =
e-rays.
K Griffith
----------
From: Katheryn Corbin=5BSMTP:corbin=40axisnet.net=5D
Sent: Thursday, November 20, 1997 12:36 PM
To: Multiple recipients of list CLAYART
Subject: Cone 6 glaze with BaCO3
----------------------------Original message----------------------------
Dear Forum...
How stable is barium when it is fired to cone 6?
Is it safe to use on cups?
I have just fired some porcelain cups to cone 6 and wondering if they are
stable for use.
I also used a wash of Mg.,Cobalt,Cu. for lines...is it stable at 6 if it
goes to the rim?
I have used BaCO3 and have thought the danger was in the raw state. Once
fired, when is there danger of leeching with use? At what cone is the
chemical released?
There has been much discussion on use of barium frit. Is this for safety
in the studio or for the final product?
The functional is scary.
Katheryn
http://www.axisnet.net/=7Ecorbin
Ron Roy on sat 22 nov 97
The material used in glazes is usually Barium Carbonate - if that is what
is ment in the following statement - all the statements are false!
>----------------------------Original message----------------------------
>Katheryn,
>Barium used in a glaze intended to be functional should have no more than 5%
>barium. If the glaze contains more, it will leach. Barium is more toxic to
>your body, in the fired state ( as in a glaze ) than it is in the raw state.
>Your body can absorb the barium when it is leached out into food. As a raw
>materials it is not absorbed easily, that is why they use it for barium e-rays.
>K Griffith
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
Ron Roy on sat 22 nov 97
It depends on the durability of the glaze - at all temperatures.
>----------------------------Original message----------------------------
>How stable is barium when it is fired to cone 6?
>Is it safe to use on cups?
>I have just fired some porcelain cups to cone 6 and wondering if they are
>stable for use.
>I also used a wash of Mg.,Cobalt,Cu. for lines...is it stable at 6 if it
>goes to the rim?
>I have used BaCO3 and have thought the danger was in the raw state. Once
>fired, when is there danger of leeching with use? At what cone is the
>chemical released?
Ron Roy
93 Pegasus Trail
Scarborough,Canada
M1G 3N8
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
Don Prey on sun 23 nov 97
I hope someone will have the time to go into a little detail on this latest
post. It's a bit late for me right now....but do want to make sure that
people recognize that we are talking about two differ ant things
here.....barium carbonate used in glazes and barium sulfate used as an aid in
medical x-rays. The human response to these two compounds is very different.
Don Prey in Oregon
Fay & Ralph Loewenthal on sun 23 nov 97
Dear K Griffith, please check the archives about Barium
Carbonate and what Monona Rossel had to say amongst
others. Barium Carbonate is bad one in the raw state as
well. It leaches through your skin. We have one major
garden pot manufacturer here who processes her own clay
and removes the salt from it with Barium Carbonate. She
goes to extreme lengths to protect her employees from it.
The Barium used for X-rays is Barium Sulfate, Barytes,
this is not toxic. There are some top fundis on Clayart so
you can always check with them. Hope this helps Ralph in
PE SA
Craig Martell on sun 23 nov 97
At 01:04 PM 11/21/97 EST, you wrote:
>----------------------------Original message----------------------------
>Katheryn,
>Barium used in a glaze intended to be functional should have no more than 5%
>barium. If the glaze contains more, it will leach. Barium is more toxic to
>your body, in the fired state ( as in a glaze ) than it is in the raw state.
>Your body can absorb the barium when it is leached out into food. As a raw
>materials it is not absorbed easily, that is why they use it for barium e-rays.
>K Griffith
Hi:
May I respectfully disagree with some of the above points?
The form of Barium used in x-rays for the lower GI tract, is Barium Sulfate,
not Barium Carb. Barium Sulfalte has no effect on the human body and being
inert, passes through. Raw Barium Carb is another matter and IS more
dangerous to humans in the raw state, than in the fired state, as in glazes.
Considering the 5% limit of barium in glazes. The general rule is that you
must have at least 3 times more silica than baria in the molecular formula
for the glaze to be considered safe for functional use. So the amount of
Barium in glazes is relative to the silica content and other oxides as well.
Glazes for functional ware that contain barium should be bright fused glazes
that don't craze, and you would still want to test for leaching.
regards, Craig Martell-Oregon
Tony Hansen on mon 24 nov 97
>Barium used in a glaze intended to be functional should have no more than =
>5=25
>barium. If the glaze contains more, it will leach. Barium is more toxic to
>your body, in the fired state ( as in a glaze ) than it is in the raw state.
>Your body can absorb the barium when it is leached out into food. As a raw
>materials it is not absorbed easily, that is why they use it for barium =
>e-rays.
I'd check this out. This has been dealt with before in detail.
There are some inaccuracies in this post.
--
-------
T o n y H a n s e n thansen@digitalfire.com
Get INSIGHT, Magic of Fire at http://digitalfire.com
Kris Griffith on mon 24 nov 97
Okay, I feel sufficiently land blasted with both private and public =
responses to
my post regarding Barium. Alright, so I may have some mis information. =
This
brings up a point. The information that I gave on the list, comes directly =
from
class notes taken just this semester in my clay and glaze materials class.
These came word for word from my notes. The point here is that it is hard =
to
know when one is getting miss information, it is therefore just as hard to =
know
when one is passing along miss information. That should be the beauty of a
forum such as this, so that we can clear up that miss information. As far =
as
the landblasting, thanks guys but you could list sources next time, =
otherwise it
is simply your word against my professors. Thanks
K. Griffith
----------
From: Craig Martell=5BSMTP:ashglaze=40teleport.com=5D
Sent: Sunday, November 23, 1997 7:32 PM
To: Multiple recipients of list CLAYART
Subject: Re: Cone 6 glaze with BaCO3
----------------------------Original message----------------------------
At 01:04 PM 11/21/97 EST, you wrote:
=3E----------------------------Original message----------------------------
=3EKatheryn,
=3EBarium used in a glaze intended to be functional should have no more than=
5=25
=3Ebarium. If the glaze contains more, it will leach. Barium is more toxic=
to
=3Eyour body, in the fired state ( as in a glaze ) than it is in the raw =
state.
=3EYour body can absorb the barium when it is leached out into food. As a =
raw
=3Ematerials it is not absorbed easily, that is why they use it for barium =
e-rays.
=3EK Griffith
Hi:
May I respectfully disagree with some of the above points?
The form of Barium used in x-rays for the lower GI tract, is Barium Sulfate,
not Barium Carb. Barium Sulfalte has no effect on the human body and being
inert, passes through. Raw Barium Carb is another matter and IS more
dangerous to humans in the raw state, than in the fired state, as in glazes.
Considering the 5=25 limit of barium in glazes. The general rule is that =
you
must have at least 3 times more silica than baria in the molecular formula
for the glaze to be considered safe for functional use. So the amount of
Barium in glazes is relative to the silica content and other oxides as well.
Glazes for functional ware that contain barium should be bright fused glazes
that don't craze, and you would still want to test for leaching.
regards, Craig Martell-Oregon
Fay & Ralph Loewenthal on wed 26 nov 97
Kris Griffiths pointed out the following:
thanks guys but you could list sources next time,
otherwise it is simply your word against my professors
This raises several questions. One is about what
information the teachers have and what is being taught to
unsuspecting and eager to learn students. The other is
that perhaps we should all make it a rule that if we are unsure about something
first. That is why they are there - to use and enhance our
knowledge. I feel that we as creative beings should use
whatever means we can to check out whatever we are told
or taught and not just accept anything at face value. I find
it an exciting challenge to test out and prove one way or
the other any information I am given. Perhaps I am in the
envious position of not having all materials and equipment
readily available, but often having to improvise and then
the need to test the improvisation. I hope this initiates
some response. Always stirring Ralph in PE SA
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