Pat Southwood on thu 2 nov 06
Thanks Ron,
Strontium is not, to my knowledge used much in the U.K.
I have heard of it, but have never had it available as a glaze material =
to test.
Thanks for letting me know of the proportions.
I will see if I can track some down.
Best wishes,
Pat southwood
Randall Moody on fri 3 nov 06
I have a question concerning the "friendliness" issue. If barium occurs
naturally in the environment then how can it be environmentally
"unfriendly"? Given the amount of material needed to actually create a
noticable impact on the environment what is the worry?
Michael Wendt on fri 3 nov 06
http://www.epa.gov/
paste this below
safewater/mcl.html#listmcl
scroll down to Barium
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Randall Moody on fri 3 nov 06
Thanks! The impact that a potter or even a group of potters would have on
the environment by using barium in a glaze would be negligible at best.
On 11/3/06, Michael Wendt wrote:
>
> http://www.epa.gov/
> paste this below
> safewater/mcl.html#listmcl
> scroll down to Barium
> Regards,
> Michael Wendt
> Wendt Pottery
> 2729 Clearwater Ave
> Lewiston, Idaho 83501
> USA
> wendtpot@lewiston.com
> www.wendtpottery.com
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Donald Burroughs on sat 4 nov 06
Randall...
Leaching and absorption are the primary concerns if I remember correctly.
Barium Carbonate's toxity is cumulative. Let me share a true story with
you. In my first year at art school ,I was admiring the work of a
undergrad thesis student who was creating these "T.V. screen" sculptures
out of a low fire clay for which she wanted a particularly "white" body
which would I guessed at the time to be vitrified. All was going fine. She
was producing anazing pieces, then one day, bang, she lands in the
hospital. She complains of being tired etc.. She tells them that she is an
art student doing a thesis in clay. The doctor on a hunch does a tox
screen and low and behold she has barium poisoning which equals her clay
body composition. For whatever reason she had made a clay body extremely
high in BC so much so that it actually leached into her blood system.
Remember this took the better part of school year, but as a first year art
student in ceramics it taught me to respect the materials I was working
with. As my professor, Robert Archambeau, has said in his notes to us
quote unquote "know your materials".
And as I have grown a little older from that time (almost eighteen years)
my practice has come to include using gloves and a mask over the years I
have worked with dry ceramic materials, and more recently using non-latex
disposable gloves when using clay I know to have unusually high quantities
of barium carb. or other toxins released into the clay itself like a
refractory body which use walnut shells = strychnine) as a filler. Believe
me that clay body is potent when being fired. So I'v come to reason that
maybe when that clay body sat in a pail over many years that the oils from
the shell would leach into the clay. Is it toxic in that state? I don't
know, but I am as sure as hell not going risk my health to find out.
Sincerely, Don Burroughs
June Perry on sat 4 nov 06
Several years ago I googled "barium toxicology" and read all the government
reports on the barium testing. According to those reports, barium carbonate is
not accumulative in the body. Their danger is in the the large amounts taken
within one short time period. People working in factories dealing with barium
all day, every day seemed the most at risk.
The body rids itself of barium, unlike some other materials which are
accumulative.
Chrome which is a carcinogenic and copper and manganese, among others, worry
me more than barium carbonate. All these things should be used with care in
the studio and in glaze formulation as well as in firing, as in the case of
manganese which releases toxic fumes on firing.
Regards,
June Perry
http://www.angelfire.com/art2/shambhalapottery/
Ron Roy on sat 4 nov 06
Hi Randall,
When it does occure "naturally" in the environment - there will be toxicity
concerns - there are drinking water limits for instance. Just because some
thing occures naturally does not mean it is benificial - or without
toxicity.
Barium carb is a well know rat poison.
In Austria there are limits as to how much is allowed to leach from hollow
ware and cookware. In Norway there are limits for hollow ware and drinking
rim, table ware and cook ware.
RR
>I have a question concerning the "friendliness" issue. If barium occurs
>naturally in the environment then how can it be environmentally
>"unfriendly"? Given the amount of material needed to actually create a
>noticable impact on the environment what is the worry?
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Vince Pitelka on sat 4 nov 06
Don Burroughs wrote:
> Leaching and absorption are the primary concerns if I remember correctly.
> Barium Carbonate's toxity is cumulative. Let me share a true story with
> you. In my first year at art school ,I was admiring the work of a
> undergrad thesis student who was creating these "T.V. screen" sculptures
> out of a low fire clay for which she wanted a particularly "white" body
> which would I guessed at the time to be vitrified. All was going fine. She
> was producing anazing pieces, then one day, bang, she lands in the
> hospital. She complains of being tired etc.. She tells them that she is an
> art student doing a thesis in clay. The doctor on a hunch does a tox
> screen and low and behold she has barium poisoning which equals her clay
> body composition. For whatever reason she had made a clay body extremely
> high in BC so much so that it actually leached into her blood system.
Don -
I'd like to see some documentation on this. NO ONE uses barium carbonate in
a claybody, except in very small percentages to eliminate scumming. It
simply is not a claybody component, and anyone who would use a large
fraction of barium carbonate in a claybody is doing their formulation
without rationale or reason. It doesn't make any sense, especially in this
age when people tend to be wary of barium. Therefore, this is a poor
example of the dangers of barium. I feel bad for the person you mention,
but she formulated her claybody in an extremely foolish manner.
Barium carbonate is a perfectly safe material in the clay studio if used
with proper safety considerations and common sense. I have complete faith
in my students to use it wisely. There is no substitute for barium
carbonate. Strontium carbonate gives different results. It really is as
simple as that.
Barium carbonate is an important glaze material that cannot be replaced. It
can be used completely safely.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Edouard Bastarache Inc. on sat 4 nov 06
Hello Vince,
right on.
Very well written !!!
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/30058682@N00/
www.thepottersshop.blogspot.com
"I'd like to see some documentation on this. NO
ONE uses barium carbonate in
a claybody, except in very small percentages to
eliminate scumming. It
simply is not a claybody component, and anyone
who would use a large
fraction of barium carbonate in a claybody is
doing their formulation
without rationale or reason. It doesn't make any
sense, especially in this
age when people tend to be wary of barium.
Therefore, this is a poor
example of the dangers of barium. I feel bad for
the person you mention,
but she formulated her claybody in an extremely
foolish manner.
Barium carbonate is a perfectly safe material in
the clay studio if used
with proper safety considerations and common
sense. I have complete faith
in my students to use it wisely. There is no
substitute for barium
carbonate. Strontium carbonate gives different
results. It really is as
simple as that.
Barium carbonate is an important glaze material
that cannot be replaced. It
can be used completely safely.
Vince Pitelka"
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/30058682@N00/
www.thepottersshop.blogspot.com
Lee Love on sat 4 nov 06
On 11/4/06, Randall Moody wrote:
> Thanks! The impact that a potter or even a group of potters would have on
> the environment by using barium in a glaze would be negligible at best.
It is the impact on the potter and his customers health that is
important, not the "environment." I have never heard an argument
against barium and glazes related to the envirionment before.
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Wes Rolley on sun 5 nov 06
>is the glaze ingredient barium the same as the
>medical grade barium they use to highlight your
>innards and colon for MRI-type tests?
>
No, the medical test use barium sulphate, which is insolluble, or very
nearly so.
--
Wes Rolley
17211 Quail Court
Morgan Hill, CA 95037
(408)778-3024
"Happiness is to be fully engaged in the activity that you believe in and, if you are very good at it, well that's a bonus." -- Henry Moore
Lee Love on sun 5 nov 06
On 11/4/06, June Perry wrote:
> Chrome which is a carcinogenic and copper and manganese, among others, worry
> me more than barium carbonate.
Why copper? Copper is a metal we have a nutritional
requirement for, for a healthy nervous system. We are having trouble
getting the mimimum daily requirement of copper because pesticides and
fertilizers leach it our of the soil crops are grown in.
Copper deficiency is implicated in BSE (search the archives.)
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Timothy Joko-Veltman on sun 5 nov 06
On 11/5/06, Lee Love wrote:
> On 11/4/06, June Perry wrote:
>
> > Chrome which is a carcinogenic and copper and manganese, among others, worry
> > me more than barium carbonate.
>
> Why copper? Copper is a metal we have a nutritional
> requirement for, for a healthy nervous system. We are having trouble
So are iron, manganese, chromium, and selenium. But all of these are
toxic in sufficient amounts - including iron, though human iron
tolerance is much higher than that of many other metals.
And I'll wager none of us are nutritionists or medical doctors - and
it is simply irresponsible to say "Go ahead, let your glaze leach
copper and manganese, the body needs them." This is in fact true
(see: http://en.wikipedia.org/wiki/Copper#Biological_role, and
http://en.wikipedia.org/wiki/Manganese#Biological_role), but the
people who buy our ware have widely varying diets and dietary needs.
Maybe one buyer has a chronic manganese deficiency and could use a
supplement, but who's to say that the piece might not be used to feed
an infant? A sustained addition of manganese to their diet could have
serious consequences.
Furthermore, how many of us know exactly how much of a "dietary
supplement" our favourite glazes are handing out, because we took the
time and money to get a good leach analysis done? How many of the
people who can say, "I do!" also know exactly how much Mn is good for
the average human (see this PDF for USFDA recommendations:
http://www.iom.edu/Object.File/Master/7/294/0.pdf (1.3MB PDF); notice
how there are different recommendations for different age groups),
much less the particular people who buy their ware?
Sorry if I'm ranting. Really, I am, but some part of me feels a deep
moral obligation to make a point of making the safest ware I can, and
of continuing to learn how (because I am well aware of how little I
know - just finding the links above taught me a lot).
> getting the mimimum daily requirement of copper because pesticides and
> fertilizers leach it our of the soil crops are grown in.
>
> Copper deficiency is implicated in BSE (search the archives.)
Maybe a pedantic question, but an important distinction, I think:
deficiency in cows or in humans?
Regards,
Tim
June Perry on sun 5 nov 06
Lee,
Copper carbonate is toxic. In fact, it is used as a garden pesticide. If you
just google copper carbonate toxicity, you'll get a page with the following
information:
Toxicity to humans, including carcinogenicity, reproductive and developmental
toxicity, neurotoxicity, and acute toxicity.
Warm regards,
June
http://www.angelfire.com/art2/shambhalapottery
Maurice Weitman on sun 5 nov 06
At 19:31 -0800 on 11/5/06, Elizabeth Priddy wrote:
>is the glaze ingredient barium the same as the
>medical grade barium they use to highlight your
>innards and colon for MRI-type tests?
no
Elizabeth Priddy on sun 5 nov 06
Students simply need to learn how to use barium
safely.
- Vince
--------------------------
This assumes that they
listened
were there that day
didn't just blow off the warning as alarmist
use appropriate protocols all the time
don't let their untrained friends "help" them
keep everrything roperly labeled
will control whether food gets in it ever
are never reckless
I just don't think toxic materials are worth the risk.
I teach children and adults. The adults are the most
likely to blow off what I said and just do it the way
they want. The kids at least try to comply.
maybe the chemistry wizes amongst the clay community
just haven't tried hard and long enough to solve the
barium substitution problem. I remember when the GB
supply dried up and the howls of the demise of all
attractive glazes rose across the land. And now there
are many. Barium provides a very specific kind of
look, its true, but if one tried hard enough, you
could get the result some other way. Strontium might
not be it, it might take a different firing
temperature or process altogether.
For a deep blue barium-esque texture and look, try
"blueberry" by Georgia Kickwheel. It is a cone 6
electric glaze.
But why not focus the energy on not using toxic
materials rather than assuming a lot of things that
are frequently not in evidence?
Some things really ought to go the way of the
dinosaur, because they are just not worth it.
Women used to paint their faces with lead infused talc
because it created a beautiful porcelain doll look, it
also poisoned them. The aesthetic changed, not the
use of lead in the powder. Arsenic used to be a
tonic. All kinds of things used to be ok. Barium is
one of them. And just because a select few are
totally safe with it doesn't make it a good idea.
I understand mel's admonition to not hide in a fallout
shelter with a hazmat suit. But there is some middle
ground. And the middle ground would be to use things
that are generally safe when used in a normal manner
in normal conditions and leave things proven to be
toxic off the menu as available ingredients. I
mean,who actually uses lead in their studio anymore?
I usually think you are on the money with your
positions regarding teaching, but in this case, I
believe you are giving students more credit than they
deserve. And I know it is a specific ceramics program
and all that, that it is not a casual art center. I
trust my instincts about people and how they work. I
would love to put a hidden camera in your glaze room
and see what the actual standards and practices are
rather than the ideal you suggest. Now that would be
enlightening and actually offer real data on the
practical real world safety of barium, even in a
teaching institution.
I know the hidden camera in a normal pottery studio
would probably curl monona's hair if it weren't curly
already.
Just something to think about, no flames to put out.
People drive without seatbelts everyday everywere.
And most of them get where they are going in one
piece, I might add. But then there are the others.
And this is not a slam on any of your specific
students, either. I certainly do not know any of them
to my knowledge. Just remarks about students and
people in general.
And full disclosure: i don't have a dog in this
fight. I use all AP and HealthLabel safe materials in
my studio classes. The Spectrum with lead and the
Ferric chloride firings are all on my lonesome and I
would never suggest or allow anyone to use them on my
1/2 acre.
You kind of surprised me with your attitude on this
topic.
E
Elizabeth Priddy
Beaufort, NC - USA
http://www.elizabethpriddy.com
____________________________________________________________________________________
Access over 1 million songs - Yahoo! Music Unlimited
(http://music.yahoo.com/unlimited)
Daniel Semler on sun 5 nov 06
Hi vince,
While I don't dispute that used with care and sense barium =20
carbonate is not nuclear waste, these statements appear overly broad.
"There is no substitute for barium carbonate. Strontium carbonate =20
gives different results. It really is as simple as that.
Barium carbonate is an important glaze material that cannot be replaced. "
In the testing that I've done on this problem it seems that in many =20
glazes a reasonable sub can be produced using strontium carbonate. Its =20
certainly true that there are glazes which rely specifically on the =20
unique contribution of barium oxide to the fired result. There are =20
others for which this is not true. Cone 10 copper reds containing =20
small amounts of barium carb. appear to be able to live without it for =20
example. Other high gloss glazes containing little barium seem to be =20
able to be subbed ok, as examples. Its in matte-land that you can have =20
problems and certainly with the classic copper barium satin matte =20
glazes are apparently impossible. Of course there are exceptions too, =20
just to prove the "rule".
Thanx
D
Michael Wendt on sun 5 nov 06
Lee,
Chromium, Manganese, Copper and other
metals are needed nutritionally only in very
small amounts. People who take nutritional
supplements for health could easily reach
dangerous levels if they are inclined to think:
"If one pill is good, two or three per day
must be better!"
Check out the EPA web site
http://www.epa.gov/safewater/mcl.html
To get to copper:
http://www.epa.gov/safewater/
(paste the address below on the end)
contaminants/
(click on copper or any of the other
metals... copper is below, just append it)
dw_contamfs/copper.html
Certainly, Barium and other toxic
metals require good care but we must
also concern ourselves with materials
we may consider safe. They are safe,
but only at certain levels. That is why
it is important to pay attention to all
housekeeping practices that affect
health and safety in the studio.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
On 11/4/06, June Perry
wrote:
> Chrome which is a carcinogenic and copper and
manganese, among others, worry
> me more than barium carbonate.
Why copper? Copper is a metal we have a
nutritional
requirement for, for a healthy nervous system. We are
having trouble
getting the minimum daily requirement of copper because
pesticides and
fertilizers leach it our of the soil crops are grown
in.
Copper deficiency is implicated in BSE
(search the archives.)
--
Lee in Mashiko, Japan
Donald Burroughs on sun 5 nov 06
Vince I can't agree with you more on the irrationality of the person I
cited in my example. "Believe it or not" what I said was true. It came from
the handler's mouth. Remember that I said it was over the school year which
is a relatively short period. Her foolish use of that material was
unfounded,but for you to say "I have complete faith in my students to use
it wisely" is incredulous if they have not been appropriately informed of
it's risks. It can be replaced by a less toxic material like strontium
and ,yes it does give different results, but "is it detrimental to the
outcome?". That is highly unlikely. Ultimately, the real point of this
discussion is , material knowledge (uses),safe material handling (MSDS data
sheets and WHMIS guidelines).
Don
Maurice Weitman on sun 5 nov 06
On 11/5/06, Lee Love wrote:
> Why copper? Copper is a metal we have a nutritional
>requirement for, for a healthy nervous system.
To which Timothy Joko-Veltman replied:
>And I'll wager none of us are nutritionists or medical doctors - and
>it is simply irresponsible to say "Go ahead, let your glaze leach
>copper and manganese, the body needs them."
>[...]
>Sorry if I'm ranting. Really, I am, but some part of me feels a deep
>moral obligation to make a point of making the safest ware I can, and
>of continuing to learn how [...]
All blessings and praise to you , Tim, for your rant and outlook.
I can't believe that some potters actually think our wares ought to
be part of a supplement delivery system.
Despite the "now, now" reassurances of my favorite Quebecois (whom I
DO believe to be indomitable AND irreducible), the notion, espoused
by others, not Edouard or Vince, that these substances (copper,
barium, etc.) are benign chemicals for which we have nutritional
requirements is very, very dangerous.
Regards,
Maurice, in Fairfax, California, who still believes that "First, do
no harm," while not really part of the Hippocratic Oath, is still a
good precept for doctors and potters to follow.
Fred Parker on sun 5 nov 06
Dear Vince Pitelka:
I am intrigued by your defense of barium carbonate.
During my relatively short tenure in glaze mixing I have become a big fan
of barium carbonate. I do my best to avoid ingesting it, and I try to
keep skin contact at a minimum. But I agree with you that barium is very
different from strontium fluxes. Proximity on the periodic table does not
necessarily mean strontium is a true "substitute." However, in reading
comments from this and other discussions I have to admit to a creeping
concern that I might be leading myself down the primrose path, especially
given my firing regimen only to cone 6.
Do you have information/opinions about barium leaching at midfire
temperatures versus higher firings?...Advice for using it as a midfire
glaze flux? I don't use it on items intended for functional (food
contact) use, nor on anything that might be used for food in spite of my
pronouncement otherwise (decorative bowls, for example). WHen I do use
it, I make it a point to keep all barium glazes on the exterior of the
piece.
With all due respect to those expressing opposing opinions on the subject,
I suspect a certain amount of the anti-barium movement -- like the anti-
lead tidal wave -- comes from a "get-on-the-bandwagon" groundswell effect
without a wholelotta factual info. For my part, I'd certainly like to see
more informed discussion about barium's proper use.
Fred Parker
On Sat, 4 Nov 2006 19:58:44 -0600, Vince Pitelka
wrote:
>
>Barium carbonate is a perfectly safe material in the clay studio if used
>with proper safety considerations and common sense. I have complete faith
>in my students to use it wisely. There is no substitute for barium
>carbonate. Strontium carbonate gives different results. It really is as
>simple as that.
>
>Barium carbonate is an important glaze material that cannot be replaced.
It
>can be used completely safely.
>- Vince
Pat Southwood on sun 5 nov 06
Hiya peeps,
Wow, I dont think that I have managed to stir up a bigger hornets nest =
in my entire life.
- Yet.!
I have passed on all of you comments to my student and asked s/he to =
come up with their own reasons why they dont want to use this particular =
material, although visually their work is screaming out for it, frankly.
When I talk of surface quality, for those not familiar with the term, I =
am referring to both the visual and tactile properties of the glaze.
I dont know how else to get that particularly sharp colour, or how else =
to obtain a glaze that allows the clay to speak as fluently.
The only other way I know is to go down the "oxide and washed back" =
route, but the colour is not up to the job.=20
My fave recipes (which are a mile away at my workshop) go from 40% =
barium up to 50%, using it as a high temp alkaline ( I presume) flux.
Adding copper and a small amount of cobalt for a really zingy non food =
safe glaze. There is also a really whizzy electric blue/purple one.
Also, you have to realise that whilst those of you accross the pond =
recoil in horror at Lead Bisilicate
we are merrily using it in the U.K. on a daily basis.............
Diff'rent strokes, I presume ?
Best Wishes, and brill to hear the various imputs,
Pat Southwood.
Good old Dora Billington.
Randall Moody on sun 5 nov 06
I am sorry if I misunderstood the original topic. I took "environmentally
friendly" to mean friendly to the environment. Did it actually mean "health
conscious" in regards to the original post? I can understand the health
issues related to barium but after looking at the data on how much barium
the person would have to ingest I have a tendency to agree with Vince.
Vince Pitelka on sun 5 nov 06
Daniel Semler wrote:
"While I don't dispute that used with care and sense barium carbonate is not
nuclear waste, these statements appear overly broad.
In the testing that I've done on this problem it seems that in many glazes a
reasonable sub can be produced using strontium carbonate. Its certainly true
that there are glazes which rely specifically on the
unique contribution of barium oxide to the fired result. There are others
for which this is not true."
Daniel -
Thanks for supporting my position. Of course barium can sometimes be
replaced with strontium with good results, but the whole point of my post is
that barium is an important glaze ingredient that produces unique results in
many glazes where strontium is not an appropriate substitute. I am glad
that we agree on that. Students simply need to learn how to use barium
safely.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Vince Pitelka on sun 5 nov 06
Donald Burroughs said:
"Her foolish use of that material was unfounded,but for you to say "I have
complete faith in my students to use it wisely" is incredulous if they have
not been appropriately informed of it's risks. It can be replaced by a less
toxic material like strontium and ,yes it does give different results, but
"is it detrimental to the outcome?". That is highly unlikely. Ultimately,
the real point of this discussion is , material knowledge (uses),safe
material handling (MSDS data sheets and WHMIS guidelines).
My goodness Donald, give me a little credit please for being a responsible
educator. OF COURSE I educate my students about the safe use of barium.
Otherwise, why in the world woudl I say "I have complete faith in my
students to use it wisely." Please use a little common sense before you post
a response like this.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Vince Pitelka on sun 5 nov 06
Fred Parker wrote:
> Do you have information/opinions about barium leaching at midfire
> temperatures versus higher firings?...Advice for using it as a midfire
> glaze flux? I don't use it on items intended for functional (food
> contact) use, nor on anything that might be used for food in spite of my
> pronouncement otherwise (decorative bowls, for example). WHen I do use
> it, I make it a point to keep all barium glazes on the exterior of the
> piece.
Fred -
I have no specific information on barium leaching at midrange temperatures,
but I would use the same caveat that you are using - don't use barium glazes
on food-contact surfaces, especially since the most interesting barium
glazes are matt glazes. If that rule is followed, and if you use proper
care in storing and handling the raw material and in mixing and using the
glazes, then I can't imagine any problems.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
Daniel Semler on sun 5 nov 06
Hi Pat,
Pat wrote :
"My fave recipes (which are a mile away at my workshop) go from 40%
barium up to 50%, using it as a high temp alkaline ( I presume) flux.
Adding copper and a small amount of cobalt for a really zingy non food
safe glaze. There is also a really whizzy electric blue/purple one."
Well at these levels subbing without change would suprise me. The
character of the glaze will be strongly dependent on the barium oxide.
And of course copper. Not likely to fly I'd guess.
But I would be interested in seeing a recipe or two one time if you
have a moment to send them, and don't mind sending them.
Thanx
D
Elizabeth Priddy on sun 5 nov 06
is the glaze ingredient barium the same as the
medical grade barium they use to highlight your
innards and colon for MRI-type tests?
E
Elizabeth Priddy
Beaufort, NC - USA
http://www.elizabethpriddy.com
__________________________________________________________________________________________
Check out the New Yahoo! Mail - Fire up a more powerful email and get things done faster.
(http://advision.webevents.yahoo.com/mailbeta)
Ric Swenson on mon 6 nov 06
hello group... I remember this thread from Clayart in 1996......
Barium sulphate is used for colonic exams... as I understand.....never had
one, but did some reading at Dartmouth Med. School, years ago, about the
medical processes....
Barium Carbonate is frequently used in ceramic glazes to promote a mate
surface....
.... and to prevent scumming in terracota.
We used it for many years at Bennington Potters with no apparent ill
effects. I saw a few extreme poison effects in the literature of
medicine... when people ATE barium by mistake.......but few examples of such
stupidity.
but..... I have only 40 years experience...perhaps others have more info?
Ric
__________________________________________________________________________________________
Check out the New Yahoo! Mail - Fire up a more powerful email and get things
done faster.
(http://advision.webevents.yahoo.com/mailbeta)
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclin
_________________________________________________________________
Use your PC to make calls at very low rates
https://voiceoam.pcs.v2s.live.com/partnerredirect.aspx
Timothy Joko-Veltman on mon 6 nov 06
On 11/6/06, Elizabeth Priddy wrote:
> is the glaze ingredient barium the same as the
> medical grade barium they use to highlight your
> innards and colon for MRI-type tests?
>
> E
>
>
> Elizabeth Priddy
No. The medical barium is barium sulfate (BaSO4, I think), and is
practically insoluble. Glazes use barium carbonate (BaCO3), which is
also used as a rat poison, can be irritating to skin and mucus
membranes, and is slightly soluble, especially in acid environments.
Read all about it in Edouard's article at ceramic-materials.info:
http://ceramic-materials.com/cermat/education/162.html
And this from Wikipedia (http://en.wikipedia.org/wiki/Barium_sulfate):
"Barium sulfate is also used as a high temperature oxidizer in certain
pyrotechnic formulas, as it produces a green colored light while it
burns. Barium nitrate is more common in green pyrotechnic formulas, as
it is a more amiable oxidizer while still producing green colored
light."
Cheers,
Tim
Lee Love on mon 6 nov 06
On 11/6/06, Elizabeth Priddy wrote:
> is the glaze ingredient barium the same as the
> medical grade barium they use to highlight your
> innards and colon for MRI-type tests?
If memory servers me from previous discussion here, the medical
barium is barium sulfate. I also recall folks trying to
substitute it for carbonate with little success.
I helped the Vet when she gave my Akita Taiko two big
syringes of the stuff prior to her surgery. She pumped it into the
corner of her mouth. I assisted, waring a lead apron, when Taiko
was Xrayed for gastric torsion. Our friend who translated us is
very pregnant and was asked to leave the area. Lit her stomach up
pretty good and it was obvious that it had flipped over and was
twisted shut at both ends.
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Lee Love on mon 6 nov 06
On 11/6/06, Vince Pitelka wrote:
> but I would use the same caveat that you are using - don't use barium glazes
> on food-contact surfaces, especially since the most interesting barium
> glazes are matt glazes.
I thought this was exactly what we were talking about.
You can put many kinds of materials in on sculpture, for
example: feces, urine and blood, that you wouldn't put on pottery.
DOH!
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Randall Moody on mon 6 nov 06
Originally the phrasing was "Does anyone have a stoneware glaze (ox or
red'n)
that has the same surface qualities as a barium glaze , but is more
acceptable to the environmentally friendly student ?" My question was not
about the possible health risks to individual people who are ingesting too
much barium but rather to the environmental impact of barium as it relates
to a studio pottery.
From everything that I have ready the amount of barium that a studio potter
would use would have negligible impact on the environment. That isn't to say
that if you over load a glaze or clay body with barium it will not have any
impact on your or someone else's health.
I also don't think Karl Rove really has an opinion on barium use in a
pottery setting so bringing him into it was just a sad little way of making
a political commentary in a subject that has nothing to do with politics.
On 11/6/06, Lee Love wrote:
>
> On 11/6/06, Vince Pitelka wrote:
>
> > but I would use the same caveat that you are using - don't use barium
> glazes
> > on food-contact surfaces, especially since the most interesting barium
> > glazes are matt glazes.
>
> I thought this was exactly what we were talking about.
>
> You can put many kinds of materials in on sculpture, for
> example: feces, urine and blood, that you wouldn't put on pottery.
> DOH!
>
>
> --
> Lee in Mashiko, Japan
> http://potters.blogspot.com/
> "Let the beauty we love be what we do." - Rumi
> "When we all do better. We ALL do better." -Paul Wellstone
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Lee Love on mon 6 nov 06
On 11/6/06, Maurice Weitman wrote:
> I can't believe that some potters actually think our wares ought to
> be part of a supplement delivery system.
Nobody ever said this. This is how Karl Rove debates, shesh! We
were comparing barium and copper. Would you prefer barium water
pipes over copper ones?
Copper glazes have been used in Mashiko for a very long time.
I would not put them in the same class as manganese and barium.
They are more like iron glazes.
A Rovian argument can be made that water is a cause of
cancer because cancer cannot exist without it.
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Lee Love on mon 6 nov 06
We need research into how we might bring copper back into every day
use as door plates,. food preparation and medical purposes. Nothing
to be afraid of. Not if you are a craftsman.
Some stuff from the archives:
http://faculty.vetmed.ucdavis.edu/faculty/docliver/Research/cuttingboard.htm
It would be interesting to see a similar comparison study
between ceramic surfaces and plastic. I am guessing our ancestors knew
what they were doing.
Also, recognizing the recent research on the beneficial
anti-bacterial effects of copper and brass containers and the copper
deficiency in modern food, if we are serious about making "food safe
glazes", should we have copper in all our food surface glazes? It may
be important, because all glazes craze with use, especially if subjected
to repeated heating. Just look at the bottom your favorite coffee mug
or tea cup. :-( ;-)
Note excerpt from article below:
/"/*The amounts that circulate into the brass water vessels would not
harm humans, Reed adds. According to the researchers, even a person
drinking 10 litres of such water in a single day would take in less than
the daily recommended dose of copper or zinc.*/ "
from Nature.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/*Drinking water stored in brass vessels good for health
Brass jugs polish off disease
Roxanne Khamsi
Traditional pitchers beat plastic in safe water stakes.
Brass water containers could combat many water-borne diseases, according
to microbiologists. The discovery suggests that these vessels should be
used in developing countries, where people typically view cheaper
plastic containers as the better option.
Water-borne diseases remain a serious threat in many poor regions of the
world, with around 2 million children dying each year from diarrhoea.
Efforts to provide safe drinking water have had difficulty reaching
remote areas.
Even in places with basic water-purification systems, people often opt
for riskier wells under trees because the water is cooler, says Rob
Reed, who led the brass study. On a recent trip to India, Reed, a
microbiologist at Northumbria University in Newcastle upon Tyne, UK,
witnessed villagers doing exactly this.
But he also heard an interesting piece of local wisdom: people believe
that traditional brass water containers offer some protection against
sickness. The idea intrigued Reed, who was in Asia investigating the
antibacterial effects of sunlight on water.
He has now found that bacteria are indeed less likely to thrive in brass
water pots than in earthenware or plastic ones. "It's one of the
traditional ideas of water treatment and we were able to find a
microbiological basis for it," he says...
...Plastic beliefs
Brass water pots also easily outperformed plastic ones, the researchers
discovered. Plastic, says Reed, did not inactivate the bacteria. But
many people in developing nations use plastic drinking vessels, because
they view them as more modern...
...Although Reed declines to speculate about exactly how many lives
could be saved by switching to brass, he points to the millions of lives
claimed each year by water-borne diseases. Storing water in brass for
two days could stop this, he suggests: "The potential is great."
*
>Antimicrobial activity of copper surfaces against suspensions of
>Salmonella enterica and Campylobacter jejuni
>Gustavo Fa=C3=BAndez , Miriam Troncoso , Paola Navarrete and Guillermo
Figueroa
>Laboratory of Microbiology, Institute of Nutrition and Food Technology,
>University of Chile. Macul 5540 Santiago, Chile
>
>Background
>
>Salmonella enterica and Campylobacter jejuni are amongst the more
>prevalent bacterial pathogens that cause foodborne diseases. These
>microorganisms are common contaminants of poultry and poultry products.
>This study was aimed to evaluate the antibacterial activity of metallic
>copper surfaces on these important enteropathogens, and to determine the
>potential acquisition of copper by food exposed to this metal.
>
>Results
>
>The antibacterial activity of copper surfaces was evaluated overlying
>them with suspensions of 106 CFU/ml of S. enterica and C. jejuni.
>Bacterial counts obtained after 0, 2, 4 and 8 hours at 10=C2=B0C and 25=C2=B0=
C
>were compared with those obtained in stainless steel and a synthetic
>polymer as control surfaces. The results showed that when these
>enteropathogens were kept in contact with copper a significant
>antibacterial activity was noted, on the contrary when the same load of
>pathogen suspensions were tested over the control surfaces it was found
>that the bacterial counts remained unchanged or even increased with
>time. The potential acquisition of copper by food exposed to this
>surface was also evaluated. Meat exposed for one hour to a copper
>surface adsorbed residual copper in a time dependant manner.
>
>Conclusions
>
>These results shows that metallic copper surfaces have an antibacterial
>activity against S. enterica and C. jejuni and suggest its potential
>application as an inhibitory agent in the various stages of the food
>processing operations.
>Putting copper into action: copper-impregnated products with potent
>biocidal activities
>Gadi Borkow and Jeffrey Gabbay
>
>E-mail contact: gadi@cupron.com
>
>Copper ions, either alone or in copper complexes, have been used for
>centuries to disinfect liquids, solids, and human tissue. Today copper
>is used as a water purifier, algaecide, fungicide, nematocide,
>molluscicide, and antibacterial and antifouling agent. Copper also
>displays potent antiviral activity. We hypothesized that introducing
>copper into clothing, bedding, and other articles would provide them
>with biocidal properties. A durable platform technology has been
>developed that introduces copper into cotton fibers, latex, and other
>polymeric materials. This study demonstrates the broad-spectrum
>antimicrobial (antibacterial, antiviral, antifungal) and antimite
>activities of copper-impregnated fibers and polyester products. This
>technology enabled the production of antiviral gloves and filters (which
>deactivate HIV-1 and other viruses), antibacterial self-sterilizing
>fabrics (which kill antibiotic-resistant bacteria, including
>methicillin-resistant Staphylococcus aureus and vancomycin-resistant
>Enterococci), antifungal socks (which alleviate symptoms of athlete's
>foot), and anti-dust mite mattress covers (which reduce mite-related
>allergies). These products did not have skin-sensitizing properties, as
>determined by guine pig maximization and rabbit skin irritation tests.
>Our study demonstrates the potential use of copper in new applications.
>These applications address medical issues of the greatest importance,
>such as viral transmissions; nosocomial, or healthcare-associated,
>infections; and the spread of antibiotic-resistant bacteria.
>
* Journal of Cattle Practise (Journal of the British Cattle Veterinary
Association)
2002, Vol 10 , Part 4, p 311-335.*
> The epidemic of BSE in the UK resulted from the combined simultaneous
> exposure of the bovine to three environmental factors; Cu chelating
> insecticides, ... .... Compulsory, exclusive high dose formulations of
> systemic phosmet warblecides penetrated the CNS and deprived PrP of
> its copper component, enabling the excesses of Mn to substitute at the
> vacant Cu domain on PrPc resulting in the formation of a non
> pathogenic, protease resistant, trivalent Mn3+ PrP isoform...
> ....Research has established that the prion protein is a
> metalloprotein which preferentially bonds onto copper or zinc at its
> octapeptide repeat region (20)(21). It seems that some hitherto
> unidentified facet of PrP's association with copper/zinc may
> eventually resolve the riddle surrounding the function of this elusive
> protein. In this respect, It is proposed that the Cu component of
> normal PrP (20)(21) may perform some role in maintaining the
> electromagnetic homeostatis of the circadian pathways; where Cu
> conducts electromagnetic energy along the circadian regulated
> melatonin - serotonergic sympathetic pathways; conducting that energy
> in order to activate a wide array of physiological functions;
> sleep/wake rhythms, sexual cycles, mood/behaviour, immune response,
> gastrointestinal rhythms, growth and repair of cells; including the
> growth of tumour cells, etc
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Lee Love on mon 6 nov 06
I want to add, where people get confused is that the original concern
about copper in glazes was in association with lead in glazes, where
it contributes to the solubility of the lead. Not because of the
dangers of handling copper to the potter. Somehow, folks have
carried over the problems with lead glazes to copper.
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Snail Scott on mon 6 nov 06
At 10:00 PM 11/5/2006 -0000, Pat S wrote:
>My fave recipes...go from 40% barium up to 50%, using it as a high temp
alkaline ( I presume) flux.
>Adding copper and a small amount of cobalt for a really zingy non food
safe glaze....
>Also, you have to realise that whilst those of you accross the pond recoil
in horror at Lead Bisilicate
>we are merrily using it in the U.K. on a daily basis...
Part of it has to do with out-of control
liability lawsuits, which, although they
are seldom directed at potters, have
created an atmosphere of caution for all
manufacturers. This atmosphere has also
created within the general public
(including artists, who are people, too)
a feeling that people ought to protected
from anything that might hurt them even
if they misuse a product outrageously.
Most of the world retains a greater sense
of personal responsibility in such matters.
Another part of this is that many folks on
this list are educators, or are working in
group settings where the biggest idiot in
the place (a normal third-grader, or an
adult doofus) is the basis for establishing
policy lest the rest of the users be hurt
by that person's un-knowledge or non-
responsibility.
Another part is that many folks on this
list are functional potters, and so the
discussion is often framed in terms of
food-safe glaze. It's an important issue,
and those of us without such constraints
don't feel much need to butt in to display
our freer approach; we just go off and do
our thing. Less-safety-critical stuff like
sculpture glaze simply doesn't need to be
discussed in the same way.
Another part is that we know we are writing
on a public forum, and those of us who
might practice freer usages in our own
studio are reluctant to say so here, for
fear of setting a bad example to those
without the knowledge to judge appropriate
use. So, we err on the side of caution.
List postings do not accurately reflect
general studio practice. Have you ever
eaten a sandwich in the studio? Stood on
the top step of a ladder? Taken the safety
guard off a tool? Run with scissors? Well,
if I have, I wouldn't say so here.
That said, I believe that knowledgeable
people should have the right to choose
their level of risk, and to choose the
level of safety that they will practice.
This is incumbent, of course, on the
free availability of information to
make people knowledgeable. It is surely
not appropriate to refuse discussion of,
say, the proper handling and use of lead
bisilicate, by saying "just don't use it
ever." Knowledge is always better than
ignorance.
-Snail
Snail Scott on mon 6 nov 06
The discussion of barium in glazes being replaced
by strontium has diverged a bit after the story
about the student who used toxic quantities in a
clay body.
Normally, only a very small amount is required to
get the desirable effect of reduced scumming in
earthenware. (I can think of no benefit to using
a toxic quantity, except as an odd choice of flux.)
The normal percentage of barium in earthenware
appears to pose no harm to the user.
'Replacement with strontium' has been advocated
in recent posts tenough to give someone the idea
that it's a good idea with clay as well. However
useful this approach is with glazes, is not one I
have ever heard of with clay bodies. I understand
that strontium does not have the same anti-
scumming effect as barium. Can someone confirm or
deny this? It's bound to come up as a question,
anyway, after this many posts discussing both
clay and glaze applications.
-Snail
John Hesselberth on mon 6 nov 06
On Nov 5, 2006, at 4:38 PM, Fred Parker wrote:
> Do you have information/opinions about barium leaching at midfire
> temperatures versus higher firings?
Hi Fred,
I'd like to comment here. There was a rather extensive study of
barium leaching published in Ceramics Technical a few years back. It
was done by Janet DeBoos. You can find it in issue No. 3 (1996). She
found that some barium glazes leach barium very significantly--some
way over 200 ppm-- and some hardly at all--less than 1 ppm. It has
been some years since I read that paper, but I remember her saying
that she wasn't prepared to draw firm conclusions. She did make some
general statements about needing enough silica + alumina and the
difficulty caused by copper.
When I was doing the research for MC6Gs and developing the 4 "rules"
for making a stable glaze (enough silica , enough alumina, melt it
thoroughly, and don't overload it with colorants) I took a look at
her results vs. the 4 rules and I thought there was at least a loose
correlation--and maybe a pretty good one. Certainly her samples that
had a silica level below 2 leached considerably. I never did a formal
correlation of her data but it would be easy enough to do--she lays
it out in a big table.
Now my work has been primarily at cone 6, but I have long been
convinced that those 4 rules apply equally well at 6 or 10 with some
minor adjustment on what will "melt well" and probably down to
earthenware temperatures as well. Her work was at cone 10 and 11 and
she saw dramatically better leaching performance at 11 than at 10.
But I don't think that had anything to do with cone per se. I think
it had to do with better melting of the glazes she was using. She
also did most of her work at fairly low Si/Al levels (4.7-5 I think).
So I suspect you can readily made stable barium-containing glazes at
cone 6 if you pay attention to what you are doing--although I have
never tried to do it. The problem with barium, from my point of view,
is in handling of the raw material (the carbonate--treat it like the
rat poison that it is) and the fact we have so many potters
formulating glazes who don't pay attention to what they are doing (or
don't care). It is not a material that beginners should be using
without careful instruction. If you ever do any formal leach testing
of barium containing glazes I'd be interested in hearing the results.
Regards,
John
Elizabeth Priddy on mon 6 nov 06
Students simply need to learn how to use barium
safely.
- Vince
--------------------------
This assumes that they
listened
were there that day
didn't just blow off the warning as alarmist
use appropriate protocols all the time
don't let their untrained friends "help" them
keep everrything roperly labeled
will control whether food gets in it ever
are never reckless
I just don't think toxic materials are worth the risk.
I teach children and adults. The adults are the most
likely to blow off what I said and just do it the way
they want. The kids at least try to comply.
maybe the chemistry wizes amongst the clay community
just haven't tried hard and long enough to solve the
barium substitution problem. I remember when the GB
supply dried up and the howls of the demise of all
attractive glazes rose across the land. And now there
are many. Barium provides a very specific kind of
look, its true, but if one tried hard enough, you
could get the result some other way. Strontium might
not be it, it might take a different firing
temperature or process altogether.
For a deep blue barium-esque texture and look, try
"blueberry" by Georgia Kickwheel. It is a cone 6
electric glaze.
But why not focus the energy on not using toxic
materials rather than assuming a lot of things that
are frequently not in evidence?
Some things really ought to go the way of the
dinosaur, because they are just not worth it.
Women used to paint their faces with lead infused talc
because it created a beautiful porcelain doll look, it
also poisoned them. The aesthetic changed, not the
use of lead in the powder. Arsenic used to be a
tonic. All kinds of things used to be ok. Barium is
one of them. And just because a select few are
totally safe with it doesn't make it a good idea.
I understand mel's admonition to not hide in a fallout
shelter with a hazmat suit. But there is some middle
ground. And the middle ground would be to use things
that are generally safe when used in a normal manner
in normal conditions and leave things proven to be
toxic off the menu as available ingredients. I
mean,who actually uses lead in their studio anymore?
I usually think you are on the money with your
positions regarding teaching, but in this case, I
believe you are giving students more credit than they
deserve. And I know it is a specific ceramics program
and all that, that it is not a casual art center. I
trust my instincts about people and how they work. I
would love to put a hidden camera in your glaze room
and see what the actual standards and practices are
rather than the ideal you suggest. Now that would be
enlightening and actually offer real data on the
practical real world safety of barium, even in a
teaching institution.
I know the hidden camera in a normal pottery studio
would probably curl monona's hair if it weren't curly
already.
Just something to think about, no flames to put out.
People drive without seatbelts everyday everywere.
And most of them get where they are going in one
piece, I might add. But then there are the others.
And this is not a slam on any of your specific
students, either. I certainly do not know any of them
to my knowledge. Just remarks about students and
people in general.
And full disclosure: i don't have a dog in this
fight. I use all AP and HealthLabel safe materials in
my studio classes. The Spectrum with lead and the
Ferric chloride firings are all on my lonesome and I
would never suggest or allow anyone to use them on my
1/2 acre.
You kind of surprised me with your attitude on this
topic.
E
Elizabeth Priddy
Beaufort, NC - USA
http://www.elizabethpriddy.com
____________________________________________________________________________________
Sponsored Link
Degrees online in as fast as 1 Yr - MBA, Bachelor's, Master's, Associate
Click now to apply http://yahoo.degrees.info
Ivor and Olive Lewis on tue 7 nov 06
Dear Friends,
This thread reveals one of the weaknesses of this art and craft we love, =
a lack of understanding of the nature of Chemical Science.
We seem to let ourselves down when we express Chemical knowledge by =
abbreviating the names of the compounds we use. Choosing to voice the =
Metallic and silencing the Acidic nominations can cause confusion when =
there are several alternatives in our lexicon. Is it such an arduous =
task to type the complete name of a compound to which we wish to refer.
Given that Barium Carbonate decomposes when heated beyond 870 deg =
Celsius, leaving a residue of Barium Oxide which has a fusion =
temperature or 1923 deg Celsius and a known solubility in both hot and =
cold water questions might be asked. What it is doing, what happens to =
it, when it is heated to Cone 6, Cone 8 or even higher as a component of =
a glaze recipe. When used in minimal or massive quantities, is it =
incorporated into the vitreous phase of a glaze or does it remain as a =
discrete compound.
It is my opinion that we are substantially ignorant about the nature of =
the compounds we use, their behaviour when heated together as mixtures =
and the chemical properties of the resultant glazes or surface coatings. =
In the past I have suggested the Chemistry Primer by Linus Pauling, =
"General Chemistry" published by Dover for $20.00 US as a good starting =
place for those who wish gain sound tuition. You do not need to be a =
mathematician or do the student exercises in order to get a basic =
understanding of the fundamental principles, if you like, the working =
rules of Chemistry. Just the ability to read thoroughly and think =
soundly to gain some comprehension. I would also suggest, rather than =
accepting pottery and ceramic arts literature as always being reliable =
in questions of science, that alternative independent sources be =
consulted to cross reference or validate facts.
Best regards to all,
Ivor Lewis.
Redhill,
South Australia.
Ivor and Olive Lewis on tue 7 nov 06
Dear Elizabeth Priddy ,
You ask
<they use to highlight your
innards and colon for MRI-type tests? >>
I suppose in a fanatical sense the answer has to be "Yes" because Barium =
is always Barium and only Barium, a metallic element with a silver =
lustre and a relative atomic weight of 137.34. It seems to have several =
isotopes none of which appear to be radioactive.
But in the sense you infer the answer is "No" because we, as potters, =
are dealing with Barium compounds, some of which are soluble in the =
acids which exist in our Stomach and some which are not. The one used in =
medical examinations is Barium Sulphate. Elementary chemical knowledge =
tells us that Sulphate compounds are insoluble in weak Hydrochloric =
acid, on which we rely for digestion. This makes it safe to use as an =
adsorber of X-Rays.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Pat Southwood on tue 7 nov 06
Hi,
Just to clarify;
I work within Higher Education, My initial post was referring to a 3rd =
year degree student who is making thrown and altered sculptural forms.
Of course they take the precautions they have been taught.
They wouldnt be allowed in the glaze room unsupervised if we didnt know =
that for sure.
I would never in a million years let anyone put a barium glaze on =
anything even vaguely functional.
Someone asked for some recipes so they could see if any subs were =
possible; =20
Mel if you dont want to post this, I understand
I am NOT advocating these, merely informing.
WARNING; A DISCLAIMER
NON FOOD SAFE BARIUM RECIPES TO FOLLOW;
Non food safe dark purple.
nepheline syenite 50
barium carbonate 50
nickel oxide 0.5%
bentonite 3
non food safe turquoise=20
nepheline syenite 56
barium carb. 25
ball clay 6
flint 7
lithium carb. 3
bentonite 3
copper carb 3% =20
1260 " oxidization=20
I have lots more, but you get the gist.
=20
N.B. THESE ARE NOT SAFE FOR ANY FORM OF DOMESTIC/ANIMAL USE.
Purely for sculptural pieces
=20
Pat.
Ron Roy on tue 7 nov 06
Hi Pat,
I think it's OK to use barium - as long as everyone knows - there is a
scull and crossed bones on the bag - so don't let pets and children drink
from the glaze buckets or lick the unglazed pots.
The problem is when they are used as liner glaze for food containers - any
barium glaze with 30 to 50 parts of barium carb are going to be unstable -
to the point they will change colour when in contact with acidic food - not
a good selling point.
Any one who says barium is a must in the diet - well I hope they are not in
charge of anything.
I would be interested if anyone has an example of a stable barium glaze by
the way - I'm sure there are some out there but who would know the
difference - any of your students? If so how are they able to tell?
RR
>Hiya peeps,
>
>Wow, I dont think that I have managed to stir up a bigger hornets nest in
>my entire life.
>- Yet.!
>I have passed on all of you comments to my student and asked s/he to come
>up with their own reasons why they dont want to use this particular
>material, although visually their work is screaming out for it, frankly.
>When I talk of surface quality, for those not familiar with the term, I am
>referring to both the visual and tactile properties of the glaze.
>I dont know how else to get that particularly sharp colour, or how else to
>obtain a glaze that allows the clay to speak as fluently.
>The only other way I know is to go down the "oxide and washed back" route,
>but the colour is not up to the job.
>My fave recipes (which are a mile away at my workshop) go from 40% barium
>up to 50%, using it as a high temp alkaline ( I presume) flux.
>Adding copper and a small amount of cobalt for a really zingy non food
>safe glaze. There is also a really whizzy electric blue/purple one.
>Also, you have to realise that whilst those of you accross the pond recoil
>in horror at Lead Bisilicate
>we are merrily using it in the U.K. on a daily basis.............
>Diff'rent strokes, I presume ?
>
>Best Wishes, and brill to hear the various imputs,
>Pat Southwood.
>Good old Dora Billington.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on tue 7 nov 06
Tim makes some very sensible points here.
If we find - through testing - that we have a deficiencies - like copper
for instance - we should supplement using a controlled dose. If we don't
have a deficiency we should not be getting more, and possibly a toxic
amount, from the pottery we store food in and eat from.
We, as makers of food containers, are not supposed to be providing trace
elements to our customers unless of course we notify them and make sure the
dose is regulated and the same each time.
If we do the studies and experiments designed to show there is no harm -
then perhaps we can say some heavy metals are benign - in the mean time we
should be learning how to make stable glazes - and we should know how to
spot an unstable glaze and make sure it's "friendly" - sans toxic oxides.
RR
>> > Chrome which is a carcinogenic and copper and manganese, among others,
>>worry
>> > me more than barium carbonate.
>>
>> Why copper? Copper is a metal we have a nutritional
>> requirement for, for a healthy nervous system. We are having trouble
>
>So are iron, manganese, chromium, and selenium. But all of these are
>toxic in sufficient amounts - including iron, though human iron
>tolerance is much higher than that of many other metals.
>
>And I'll wager none of us are nutritionists or medical doctors - and
>it is simply irresponsible to say "Go ahead, let your glaze leach
>copper and manganese, the body needs them." This is in fact true
>(see: http://en.wikipedia.org/wiki/Copper#Biological_role, and
>http://en.wikipedia.org/wiki/Manganese#Biological_role), but the
>people who buy our ware have widely varying diets and dietary needs.
>Maybe one buyer has a chronic manganese deficiency and could use a
>supplement, but who's to say that the piece might not be used to feed
>an infant? A sustained addition of manganese to their diet could have
>serious consequences.
>
>Furthermore, how many of us know exactly how much of a "dietary
>supplement" our favourite glazes are handing out, because we took the
>time and money to get a good leach analysis done? How many of the
>people who can say, "I do!" also know exactly how much Mn is good for
>the average human (see this PDF for USFDA recommendations:
>http://www.iom.edu/Object.File/Master/7/294/0.pdf (1.3MB PDF); notice
>how there are different recommendations for different age groups),
>much less the particular people who buy their ware?
>
>Sorry if I'm ranting. Really, I am, but some part of me feels a deep
>moral obligation to make a point of making the safest ware I can, and
>of continuing to learn how (because I am well aware of how little I
>know - just finding the links above taught me a lot).
>
>> getting the mimimum daily requirement of copper because pesticides and
>> fertilizers leach it our of the soil crops are grown in.
>>
>> Copper deficiency is implicated in BSE (search the archives.)
>
>Maybe a pedantic question, but an important distinction, I think:
>deficiency in cows or in humans?
>
>Regards,
>
>Tim
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on tue 7 nov 06
Hi Randall,
I think the intent of the original post was about human toxicity but I also
believe misleading because of the "environmentally." Perhaps I am wrong in
my assumption?
The simplistic view is not the only view - Barium is an effective rat
poison - so you can also consider what the effect of serious Barium
leaching into food would have on a one pound fetus.
I don't think anyone is saying it's OK to use a seriously unstable barium
glazes as a liner - I think we are finally past that particular fantasy.
The question is - how much Barium do you feel right about leaching into
your customers food.
Some potters think none is the right answer in view of the absence of solid
data on what might be unhealthy.
RR
>I am sorry if I misunderstood the original topic. I took "environmentally
>friendly" to mean friendly to the environment. Did it actually mean "health
>conscious" in regards to the original post? I can understand the health
>issues related to barium but after looking at the data on how much barium
>the person would have to ingest I have a tendency to agree with Vince.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Pat Southwood on tue 7 nov 06
Hi Ron
The original question was primarily concerned with the effects of mining
Bariun, and secondarily concerned with it's toxicity.
Best Wishes,
Pat Southwood
----- Original Message -----
From: "Ron Roy"
To:
Sent: Tuesday, November 07, 2006 5:43 PM
Subject: Re: env. friendly barium glazes
> Hi Randall,
>
> I think the intent of the original post was about human toxicity but I
> also
> believe misleading because of the "environmentally." Perhaps I am wrong in
> my assumption?
>
> The simplistic view is not the only view - Barium is an effective rat
> poison - so you can also consider what the effect of serious Barium
> leaching into food would have on a one pound fetus.
>
> I don't think anyone is saying it's OK to use a seriously unstable barium
> glazes as a liner - I think we are finally past that particular fantasy.
> The question is - how much Barium do you feel right about leaching into
> your customers food.
>
> Some potters think none is the right answer in view of the absence of
> solid
> data on what might be unhealthy.
>
> RR
>
>
>
>
>>I am sorry if I misunderstood the original topic. I took "environmentally
>>friendly" to mean friendly to the environment. Did it actually mean
>>"health
>>conscious" in regards to the original post? I can understand the health
>>issues related to barium but after looking at the data on how much barium
>>the person would have to ingest I have a tendency to agree with Vince.
>
> Ron Roy
> RR#4
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Kathy Stecker on tue 7 nov 06
Hello to all,
As we are discussing the use of barium in glazes, I wanted to remind you of
the info that Edouard Bastarache, who is actually both potter and involved in
toxicology research has provided us during the last round of discussion. He
is responding to the questions that Ron Roy had asked if you get confused. The
half life of barium seems a really important factor here-half of it leaves
your body in less than a day when lead and cadmium last years and years. So
with barium it seems hard to consider it to be anywhere the issue as the others
I was a bit surprised when the issue dropped and nothing more was said last
round-seems every new book everyone repeats warnings and newbies may get
overzealous and don't really get a full picture. please look at this link:
_http://lsv.ceramics.org/scripts/wa.exe?A2=ind0507B&L=CLAYART&P=R14386&D=0_
(http://lsv.ceramics.org/scripts/wa.exe?A2=ind0507B&L=CLAYART&P=R14386&D=0)
Thanks and before anyone gets concerned-I like to use liner glazes myself.
And after working in a chem lab for years have a very healthy respect for my
materials and safety in general. I also really respect all the knowledge and
differing views everyone has to share. I have a long way to go myself.
OK rave over just really interested in more discussion on the basic facts of
the half life
Kathy Stecker
Winter Springs, Florida USA
(http://lsv.ceramics.org/scripts/wa.exe?A2=ind0507B&L=CLAYART&P=R14386&D=0)
Edouard Bastarache Inc. on tue 7 nov 06
Hello Pat,
here is your answer about mining
"Hi Ron
The original question was primarily concerned with
the effects of mining
Bariun, and secondarily concerned with it's
toxicity.
Pat"
Pulmonary Effects :
Handling of pulverulent barium sulphate was
accompanied, at the time of already old
observations, by benign pneumonias generally
resulting in pulmonary radiological images
consisting of nodules disseminated in both lung
fields without clinical symptoms, nor anomalies of
respiratory functional tests, it is barytosis.
It also occurs during significant exposures to
lithopone and barium oxide. On the other hand,
serious fibrosis was reported among workers of
barium mines because of the presence of crystaline
silica in the ore.
Edouard Bastarache
Le Français Volant
The Flying Frenchman
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://perso.wanadoo.fr/smart2000/index.htm
http://www.pshcanada.com/Toxicology.htm
http://www.flickr.com/photos/30058682@N00/
www.thepottersshop.blogspot.com
Lee Love on tue 7 nov 06
On 11/6/06, Randall Moody wrote:
> From everything that I have ready the amount of barium that a studio potter
> would use would have negligible impact on the environment. That isn't to say
> that if you over load a glaze or clay body with barium it will not have any
> impact on your or someone else's health.
Randall,
From reading Jared Diamond's book, Collapse, the large
percentage of the environmental impact of mining minerals and metals
are in their excavation, up front, because of the high ration of waste
taken out of the ground to get a usable amount of mineral or metal.
It is related to the "flush toilet syndrome". Because the
impact is tidy at our end, we don't realize the resources that were
required to provide the resource to us.
Things like oil have fewer waste products in their mining.
About 1 to 1 waste to usable oil. Big eye opener for me. I can
get you data if you are interested. Not for barium, but for other
minerals and metals.
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Lee Love on wed 8 nov 06
Here are some figures related to environmental impact, from Jared
Diamond's Collaspe:
Waste to ore ratios:
oil 1:1 (waste is mostly water)
coal 1:1
copper 400:1
gold 5,000,000:1
Please VOTE everyone. It is your licenses to bitch!
--
Lee in Mashiko, Japan
http://potters.blogspot.com/
"Let the beauty we love be what we do." - Rumi
"When we all do better. We ALL do better." -Paul Wellstone
Randall Moody on thu 9 nov 06
Okay now boil those numbers down to the individual usage by sector. My point
is that the barium used in studio potteries is such that the impact from the
mining of that amout is negligible. Plus add in that if every studio potter
on the planet stopped using barium in the relativly few glazes that call for
it then the impact on the mining of barium would also be miniscule. Do you
have any other sources to back up your ascertions? I find the waste to ore
ratio for coal to be especially dubious after having seen the results of
open pit mining.
Randall
On 11/7/06, Lee Love wrote:
>
> Here are some figures related to environmental impact, from Jared
> Diamond's Collaspe:
>
> Waste to ore ratios:
>
> oil 1:1 (waste is mostly water)
> coal 1:1
> copper 400:1
> gold 5,000,000:1
>
>
>
> Please VOTE everyone. It is your licenses to bitch!
>
> --
> Lee in Mashiko, Japan
> http://potters.blogspot.com/
> "Let the beauty we love be what we do." - Rumi
> "When we all do better. We ALL do better." -Paul Wellstone
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Ivor and Olive Lewis on fri 10 nov 06
Dear Randall Moody,
Perhaps the adverse footprint of Barium compounds used by ceramic =
artists is minimal but it is extensively mined for other reasons. It is =
used to make dense (Heavy) mud used to clear drilling wastes during oil =
exploration.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Randall Moody on fri 10 nov 06
I will agree to that but even if every potter in the world stopped using
barium in his or her glazes the over all effect on the production and mining
of barium wouldn't make a hill of beans.
On 11/10/06, Ivor and Olive Lewis wrote:
>
> Dear Randall Moody,
>
> Perhaps the adverse footprint of Barium compounds used by ceramic artists
> is minimal but it is extensively mined for other reasons. It is used to make
> dense (Heavy) mud used to clear drilling wastes during oil exploration.
>
> Best regards,
>
> Ivor Lewis.
> Redhill,
> South Australia.
>
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
| |
|
