Megan Ratchford on wed 3 apr 02
Howard,
I've been using the Laguna cone 10 variant of a manganese clay body. I
just love it. Because of the manganese the unglazed body is lustrous after
the glaze firing. I do not allow myself to throw large amounts of this all
at once. It's used for special large pieces. But I would use it every day
all day long for all of my production work if I wasn't worried about the
health issues.
Okay, Just my two cents!
Megan
----- Original Message -----
From: "Axner Co."
To:
Sent: Wednesday, April 03, 2002 7:30 AM
Subject: Black Clay Safety Inquiry
> Dear Clay Art Members,
>
> I would like to get some information from you with regards to possible
> health risks associated with making and using black clay.
>
> Twenty-five years ago, I used black clay in my own pottery production and
> found it to be beautiful. I had it custom made for me from my own
> formulations (this was way before I started making clay). I know a
> number of people who use black clay now and make beautiful pots with it.
> We at Axner have the capability of making black clay now but I have
> refused to so due to the fact that I am of the impression that black clay
> bodies can pose a serious health risk, depending on how they are made.
> In particular, I am concerned with the use of Magnesium Dioxide. I know
> one potter and heard of a number of others who have had very serious
> health problems that were said to be due to exposure to Magnesium
> Dioxide. I would like to know if anyone has more information as to the
> accuracy of this and I would like to know if anyone else knows of people
> who have had problems due to exposures to this or other chemicals. I
> have heard things in an antidotal fashion, and I am interested in getting
> more antidotal information, but I am far more interested in getting some
> facts that are based on citeable research.
>
> By the way, we offer a series of colored clays (including black) in small
> quantities. They are made with Mason Stains in a way that I believe are
> not a health hazard. It is too expensive to make clay in this fashion
> for anything other than very small works.
>
> Howard Axner
>
>
____________________________________________________________________________
__
> 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.
Axner Co. on wed 3 apr 02
Dear Clay Art Members,
I would like to get some information from you with regards to possible
health risks associated with making and using black clay.
Twenty-five years ago, I used black clay in my own pottery production and
found it to be beautiful. I had it custom made for me from my own
formulations (this was way before I started making clay). I know a
number of people who use black clay now and make beautiful pots with it.
We at Axner have the capability of making black clay now but I have
refused to so due to the fact that I am of the impression that black clay
bodies can pose a serious health risk, depending on how they are made.
In particular, I am concerned with the use of Magnesium Dioxide. I know
one potter and heard of a number of others who have had very serious
health problems that were said to be due to exposure to Magnesium
Dioxide. I would like to know if anyone has more information as to the
accuracy of this and I would like to know if anyone else knows of people
who have had problems due to exposures to this or other chemicals. I
have heard things in an antidotal fashion, and I am interested in getting
more antidotal information, but I am far more interested in getting some
facts that are based on citeable research.
By the way, we offer a series of colored clays (including black) in small
quantities. They are made with Mason Stains in a way that I believe are
not a health hazard. It is too expensive to make clay in this fashion
for anything other than very small works.
Howard Axner
Jennifer Assinck on wed 3 apr 02
First, black clay is often coloured with MANGANESE dioxide, not magnesium dioxide. The two names are often interchange, but the first one is very toxic.
There was a potter in my guild, before my time, who threw with a clay body with manganese speckles. She developed severe neurological damage and could no longer pot.
PSH (Pottery Supply House) in Oakville, Ontario, Canada, sells cone 6 black clay made of chromite ore. Here is what their web site catalogue says:
http://www.pshcanada.com/p/clay1.htm
"A unique, multipurpose black cone 6 clay incorporating chromite ore, a naturally occurring stain. Food surfaces, especially those fired below cone 6, must be glazed."
For myself, I made a slip using my own clay body and coloured it with iron chromate (synthetic source, as opposed to the iron chromite ore) because I happened to have a lot on hand.
Instead of colouring the whole body of clay, I decided to use this slip to cover the clay I usually throw, a porcelain. That way I did not contaminate my wheel head and pan with dark clay. This technique has worked well for me.
In addition, by using a slip to colour your work, you avoid having to trim black clay and risk creating black clay dust in the studio from errant scraps, no matter what the colourant is.
(By the way, most stains contain manganese so that does not make them any safer than using manganese directly.)
Regards,
Jennifer Assinck
Newmarket, Ontario, Canada
>
> From: "Axner Co."
> Date: 2002/04/03 Wed AM 09:30:47 EST
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Black Clay Safety Inquiry
>
> Dear Clay Art Members,
>
> I would like to get some information from you with regards to possible
> health risks associated with making and using black clay.
>
> Twenty-five years ago, I used black clay in my own pottery production and
> found it to be beautiful. I had it custom made for me from my own
> formulations (this was way before I started making clay). I know a
> number of people who use black clay now and make beautiful pots with it.
> We at Axner have the capability of making black clay now but I have
> refused to so due to the fact that I am of the impression that black clay
> bodies can pose a serious health risk, depending on how they are made.
> In particular, I am concerned with the use of Magnesium Dioxide. I know
> one potter and heard of a number of others who have had very serious
> health problems that were said to be due to exposure to Magnesium
> Dioxide. I would like to know if anyone has more information as to the
> accuracy of this and I would like to know if anyone else knows of people
> who have had problems due to exposures to this or other chemicals. I
> have heard things in an antidotal fashion, and I am interested in getting
> more antidotal information, but I am far more interested in getting some
> facts that are based on citeable research.
>
> By the way, we offer a series of colored clays (including black) in small
> quantities. They are made with Mason Stains in a way that I believe are
> not a health hazard. It is too expensive to make clay in this fashion
> for anything other than very small works.
>
> Howard Axner
>
> ______________________________________________________________________________
> 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.
>
Wanda Holmes on wed 3 apr 02
There is a potter here in Austin, who also suffered neurological damage from
using black clay with manganese. It is not severe, but she is definitely
aware of it. She admits, however, that she took no precautions in dealing
with it and used it quite heavily. Wanda
-----Original Message-----
From: Ceramic Arts Discussion List [mailto:CLAYART@LSV.CERAMICS.ORG]On
Behalf Of Jennifer Assinck
Sent: Wednesday, April 03, 2002 1:56 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Black Clay Safety Inquiry
First, black clay is often coloured with MANGANESE dioxide, not magnesium
dioxide. The two names are often interchange, but the first one is very
toxic.
There was a potter in my guild, before my time, who threw with a clay body
with manganese speckles. She developed severe neurological damage and could
no longer pot.
PSH (Pottery Supply House) in Oakville, Ontario, Canada, sells cone 6 black
clay made of chromite ore. Here is what their web site catalogue says:
http://www.pshcanada.com/p/clay1.htm
"A unique, multipurpose black cone 6 clay incorporating chromite ore, a
naturally occurring stain. Food surfaces, especially those fired below cone
6, must be glazed."
For myself, I made a slip using my own clay body and coloured it with iron
chromate (synthetic source, as opposed to the iron chromite ore) because I
happened to have a lot on hand.
Instead of colouring the whole body of clay, I decided to use this slip to
cover the clay I usually throw, a porcelain. That way I did not contaminate
my wheel head and pan with dark clay. This technique has worked well for
me.
In addition, by using a slip to colour your work, you avoid having to trim
black clay and risk creating black clay dust in the studio from errant
scraps, no matter what the colourant is.
(By the way, most stains contain manganese so that does not make them any
safer than using manganese directly.)
Regards,
Jennifer Assinck
Newmarket, Ontario, Canada
>
> From: "Axner Co."
> Date: 2002/04/03 Wed AM 09:30:47 EST
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Black Clay Safety Inquiry
>
> Dear Clay Art Members,
>
> I would like to get some information from you with regards to possible
> health risks associated with making and using black clay.
>
> Twenty-five years ago, I used black clay in my own pottery production and
> found it to be beautiful. I had it custom made for me from my own
> formulations (this was way before I started making clay). I know a
> number of people who use black clay now and make beautiful pots with it.
> We at Axner have the capability of making black clay now but I have
> refused to so due to the fact that I am of the impression that black clay
> bodies can pose a serious health risk, depending on how they are made.
> In particular, I am concerned with the use of Magnesium Dioxide. I know
> one potter and heard of a number of others who have had very serious
> health problems that were said to be due to exposure to Magnesium
> Dioxide. I would like to know if anyone has more information as to the
> accuracy of this and I would like to know if anyone else knows of people
> who have had problems due to exposures to this or other chemicals. I
> have heard things in an antidotal fashion, and I am interested in getting
> more antidotal information, but I am far more interested in getting some
> facts that are based on citeable research.
>
> By the way, we offer a series of colored clays (including black) in small
> quantities. They are made with Mason Stains in a way that I believe are
> not a health hazard. It is too expensive to make clay in this fashion
> for anything other than very small works.
>
> Howard Axner
>
>
____________________________________________________________________________
__
> 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.
>
____________________________________________________________________________
__
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.
Edouard Bastarache on wed 3 apr 02
Hello Howard,
It is not Magnesium Dioxide but Manganese Dioxide.
I have heard of 2 cases diagnosed in Montreal at the end of the
seventies or beginning of the eighties. The were unskilled workers
making manganese-containing clays.
It is a matter of particle size distribution, level of exposure and
duration etc.
Manganese & inorganic compounds
Compounds :
Manganese compounds used by potters are inorganic , like manganese dioxid=
e,
oxide
and manganese carbonate.
Uses :
Metallic applications account for most manganese consumption, with about
90%
used in steelmaking.
Slags coming from old converters, as in the Thomas process in the steel
industry, can be
used as fertilizers.
Certain welding operations require the use of electrodes whose coating o=
r
alloyed core contains manganese.
The chemical industry uses manganese as a catalyst.
Permaganates are powerful oxidizers.
Manganese has also different other uses
-As a coloring material
- In the manufacture of dry cells
- In the manufacture of pesticides(Maneb)
- As food additives for livestock
- In the composition of fertilizers
- In pharmaceutical products
- As siccative for paints
- In wood preservatives
- In leather processing
Manganese is an essential mineral for humans and animals. It is necessary
for
normal bone formation. It has been estimated that a normal 70-kg man has =
a
total of
12mg to 20 mg in his body.
Exposure :
The inorganic compounds do not penetrate the body via skin like some orga=
nic
compounds, such as certain tricarbonyls.
Inhalation of dust or fume is the major route of entry in occupational
manganese poisonning. Also inhaled large particles are ingested after
mucociliary clearance from the lungs. Gastrointestinal absorption is
generally low (5%). Very few poisonings have occured after ingestion.
Acute intoxication ;
1-Metal fume fever :
Inhalation of manganse oxide fumes may cause a flu-like syndrome similar =
to
=AB metal fume fever =BB, treatment is symptomatic.
2-Chemical pneumonia :
In the case of severe exposure to fumes or dust of various manganese salt=
s,
a severe chemical pneumonia may occur.
3-Acute intoxication by ingestion :
Acute intoxication by ingestion rarely occurs and is caused by accidental=
or
voluntary ingestion of a manganese salt(as the ingestion of tablets of
potassium permaganate), this chemical causes massive burns of the digesti=
ve
tract, oedema of the upper respiratory tract and circulatory collapse.
Chronic intoxication :
The primary target organ of manganese toxicity is the central nervous
system, particularly the extra-pyramidal system; the lungs may also be
injured in the case of chronic exposure to manganese.
1-Central nervous system :
Neurological symptoms are caused by inhalation of fumes or dusts of
manganese.
The extra-pyramidal system is the main target organ of manganese.
Exposure to heavy concentrations of dusts or fumes for as little as three
months may
produce the condition, but usually cases develop after 1-3 years of
exposure.
In manganese mines where most cases have occurred, the disease has appear=
ed
after
10 to 20 years of exposure.
The symptoms may simulate progressive bulbar paralysis, postencephalitic
Parkinsonism, multiple sclerosis, amyotrophic lateral sclerosis and
progressive lenticular degeneration (Wilson's disease).
The best way to diagnose, at an early stage, manganese intoxication is
neurological examination.
A standardized questionnaire of neurological symptoms is helpful.
Here are some symptoms, among others, to be looked for in chronic mangan=
ese
intoxication:
-nervousness
-irritability
-memory loss
-tiredness
-insomnia
-muscle weakness
-muscle pain
-trembling fingers
-stiffness of limbs
-difficulty with fine movements
-stuttering
-hoarse voice
-urinary problems
-impotence.
At physical examination your doctor should look for signs of an
extra-pyramidal syndrome at its beginning.
2-Respiratory tract :
Pulmonary tissue does not seem to be the critical target organ of mangane=
se
during chronic exposure.
On the other hand, various respiratory symptoms (acute and chronic
bronchitis, pneumonia, functional changes of the obstructive type) were
observed among workers exposed chronically to manganese at levels higher
than those which cause slight neurological disturbances in certain worker=
s.
Reproduction :
Manganese could disturb libido according to certain studies. It was
demonstrated that a loss of libido and impotence, sometimes preceded by =
a
phase of hypersexuality, was observed among subjects suffering from
manganism.
There are contradictory reports as for the effects of manganese on
reproduction; however, certain studies showed a reduction in the number o=
f
children fathered by male workers during the time when they were exposed =
to
manganese.
In Russia, an excess of spontaneous miscarriages occurred among wives of
workers employed in manganese treatment plants.
Teratogenesis :
No teratogenic action due to manganese has been described in man.
Mutagenesis and carcinogenesis :
The manganese ion has not caused modifications in the DNA among mammals.
In the literature there is no indication suggesting that manganese exerts=
a
cancerogenic action in man. In fact , experimental studies plead rather
against such an association.
Exposure :
The important thing is your exposure to inorganic manganese, it may vary=
if
you are a pottery factory worker, a teacher, a full-time studio potter or=
a
part-time.
The evaluation of the amount used over a given period of time in clays an=
d
glazes is essential in assessing your exposure in a non-parametric way i.=
e.
without the aid of persons specialized in the field of occupational hygie=
ne.
In the wet state, as in moist clays and glazes, these compounds are
certainly much less hazardous than as dust.
Pottery factories can financially afford the monitoring of manganese
exposure but, it is not the same for artists and craftpersons.
The threshold limit value for dusts of manganese metal and inorganic
compounds actually proposed by the ACGIH is 0.2 mg/m3,as total dust.
Prevention :
So good house keeping of your studio is very important; to do so you may,
among other things, use wet processes, or even a vacuum system whose air=
is
exhausted outside of the workshop.
Avoidance of processes generating unnecessary dust is also importan. To
this, we may add work in closed systems and improvement of the general
ventilation.
The wearing of an approved dust mask for this kind of hazard is also
recommended when the level of exposure seems too high.
Medical surveillance :
1-Pre-emploiment medical examination :
It aims at searching for the presence of a neurological and/or pulmonary
impairment likely to be worsened by exposure to manganese, and it will b=
e
used as reference making it possible to better analyze the results of
periodical examinations.
Here are some suggested elements;
1-Complete history taking and physical examination,
2-Neurological assessment,
3-Spirometry,
4-A few psychomotor tests(for instance: evaluation of extremities tremor-=
and
reaction
(response) time
5-Blood and urinary manganese measurements.
2-Periodical examination :
Its frequency depends on the severity of exposure and on the legislation=
in
force. It consists in seeking, if possible, with the aid of a well
standardized questionnaire, early symptoms of neuropsychological and
pulmonary impairment, in repeating the pre-employment examinations and
comparing them with the latter in order to detect any risk of excessive
impregnation .
It is important to practise this comparison, not only at the individual
level but, also at the level of the group of workers.
Workers exposed to manganese should have a medical examination every 3 to=
6
months
(Shunk, Tanaka and Lieben).
Experts still differ about the precision of urinary and/or blood
measurements of manganese as good indicators of exposure and intoxication=
.
Among workers, kept away from their job on a temporary basis, and from
exposure to
manganese dioxide, a good correlation was
observed between urinary and blood levels and the index of cumulative
exposure, on an individual basis(Lucchini and al.).
A correlation was also found between these tests and different
neurobehavioral tests.
But let us not forget that human data are insufficient yet for proposing =
a
a blood and/or urinary standard for manganese on an individual basis
Tanaka & Lieben however observed a correlation between the urinary
excretion and the intensity of exposure, and Japanese authors
suggested that manganese excretion higher than 40-50 micrograms/liter
corresponds to a level of exposure where lesions can occur (Horiuchi & al=
.)
=2E
Often times the only aid to diagnosis is a history of manganese exposure.
I have heard of 2 cases of Parkinson-like syndrome among unskilled worker=
s
making clays and glazes for a local pottery supplies store (Montreal) tha=
t
occurred in the 70's before Quebec passed its laws in Occupational Health
and Safety
Treatment :
At the beginning of the intoxication, it seems that a chelation treatment
with calcium EDTA may favor an improvement of the clinical picture. At an
advanced stage of the intoxication this treatment is ineffective. In this
case, the treatment is identical to Parkinson's disease (levodopa).The
usefulness of this treatment is however contoversial.
Edouard Bastarache M.D. ( Occupational & Environmental Medicine)
Author of =AB Substitutions for raw ceramic materials =BB
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
REFERENCES :
1-Occupational Medicine, Carl Zenz, last edition.
2-Occupational & Environmental Medicine, Joseph LaDou, last edition.
3-Chemical Hazards of the Workplace, Proctor & Hughes, last edition.
4-Sax's Dangerous Properties of Industrial Materials, Lewis C, last editi=
on.
5-Industrial Chemical Exposure, Lauwerys & Hoet, last edition.
6-Toxicologie Industrielle et Intoxications Professionnelles, Lauwerys
Robert,R.1999
7-Encyclopedie Medico-Chirurgicale- Toxicologie-Pathologie Professionnell=
e
Paris, Lauwerys R, et Roels H., juin 2001.
John Hesselberth on wed 3 apr 02
Hi Howard,
Assume you are talking about manganese dioxide rather than magnesium
dioxide. That's common slip of the fingers.
From all the reading I have done, the toxicity issues with manganese are
from inhalation of dust or fumes--not from ingestion or skin adsorption. In
fact you will find a little in every multivitamin and it is present in quite
a few foods. I think the questions you need to answer for yourself are how
much will be emitted during firing and/or how much will be in the air when
people who have no safety sense start sanding their greenware without a mask
on. The more finely subdivided it is, the more likely you will have fumes
given off during firing or dispersed in the air during sanding--e.g.,
granular manganese used for speckles is not thought to be a problem although
I'm not sure anyone has ever proven that. Powdered manganese dioxide like
you are talking about certainly has more potential to be a problem.
The problems with fumes are real and, unfortunately, a few potters have
learned that the hard way. If you can get your hands on a copy of Sax
"Dangerous Properties of Industrial Materials" and look under Manganese
Compounds you can read all about it. If you want I will fax you that page.
It would certainly cause me to do some careful testing before I
commercialized a black clay. I'd also have a good talk with my lawyer and
my insurance company.
There are also a handful of good industrial toxicologists you might want to
consult. I am aware of one at Duke University--I think I can still find his
name if you are interested.
Regards,
John
on 4/3/02 9:30 AM, Axner Co. at axbuyer@AO.NET wrote:
> Dear Clay Art Members,
>
> I would like to get some information from you with regards to possible
> health risks associated with making and using black clay.
>
> Twenty-five years ago, I used black clay in my own pottery production and
> found it to be beautiful. I had it custom made for me from my own
> formulations (this was way before I started making clay). I know a
> number of people who use black clay now and make beautiful pots with it.
> We at Axner have the capability of making black clay now but I have
> refused to so due to the fact that I am of the impression that black clay
> bodies can pose a serious health risk, depending on how they are made.
> In particular, I am concerned with the use of Magnesium Dioxide. I know
> one potter and heard of a number of others who have had very serious
> health problems that were said to be due to exposure to Magnesium
> Dioxide. I would like to know if anyone has more information as to the
> accuracy of this and I would like to know if anyone else knows of people
> who have had problems due to exposures to this or other chemicals. I
> have heard things in an antidotal fashion, and I am interested in getting
> more antidotal information, but I am far more interested in getting some
> facts that are based on citeable research.
>
> By the way, we offer a series of colored clays (including black) in small
> quantities. They are made with Mason Stains in a way that I believe are
> not a health hazard. It is too expensive to make clay in this fashion
> for anything other than very small works.
>
> Howard Axner
>
> ______________________________________________________________________________
> 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.
Web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
Email: john@frogpondpottery.com
"The life so short, the craft so long to learn." Chaucer's translation of
Hippocrates, 5th cent. B.C.
vince pitelka on wed 3 apr 02
When I was doing research for my book, I communicated a lot with Edouard
Bastarache, who is a frequent contributor to this list and is an MD and a
toxicologist. I do not know if he is monitoring it right now. He assured
me that the standard ceramic oxides are safe for skin contact and cannot be
absorbed through the skin. The toxicity problems exist in breathing the
dust, and in the firing, some oxides (especially manganese) give off highly
toxic
fumes.
We see a lot of well-meaning but very careless and irresponsible "advice" on
Clayart concerning toxicity issues. It does no good to be an alarmist about
these things unless your facts are solid. Either take the time to do your
research, or else DO NOT post "warnings" about supposedly toxic materials.
Jennifer wrote:
> (By the way, most stains contain manganese so that does not make them any
> safer than using manganese directly.)
The above is a good example. First of all, most stains do not contain
manganese. And of course, one of the primary REASONS they make fritted
materials is to eliminate toxicity resulting from soluble compounds in raw
materials. That would not be a concern with most of the coloring oxides we
work with, because they are benign in skin contact, but the whole point is
that any ceramic material in a frit is sealed in a glass, and while you
certainly have to worry about toxicity in
inhalation (silica dust), you do not have to worry about skin absorption
risks.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Jennifer Assinck on thu 4 apr 02
Sorry Vince, et al. I meant to say most BLACK stains (that I have seen the
formulation for), not most stains.
Jennifer
Jennifer wrote:
> (By the way, most stains contain manganese so that does not make them any
> safer than using manganese directly.)
The above is a good example. First of all, most stains do not contain
manganese.
Best wishes -
- Vince
Jennifer F Boyer on thu 4 apr 02
Do you think Cone 6 speckled clay with granular manganese would
give off as many fumes as a heavy manganese glaze? There seem to
be a lot of speckled clays in the catalogues these days. I'm
imagining there are manganese fumes in the bisk and glaze
firings of these manganese bearing clays even if you use safe
glazes. But I'm wondering how much, since the manganese is
dispersed in the granular form throughout the clay.
Any ideas how paranoid we should be?
Jennifer
vince pitelka wrote:
>
> When I was doing research for my book, I communicated a lot with Edouard
> Bastarache, who is a frequent contributor to this list and is an MD and a
> toxicologist. I do not know if he is monitoring it right now. He assured
> me that the standard ceramic oxides are safe for skin contact and cannot be
> absorbed through the skin. The toxicity problems exist in breathing the
> dust, and in the firing, some oxides (especially manganese) give off highly
> toxic
> fumes.
>
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Jennifer Boyer mailto:jboyer@adelphia.net
Thistle Hill Pottery
95 Powder Horn Glen Rd
Montpelier, VT 05602 USA
802-223-8926
http://www.thistlehillpottery.com/
Never pass on an email warning without checking out this site
for web hoaxes and junk:
http://urbanlegends.about.com/
~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
Brenda Z on thu 4 apr 02
Vince said:
> ...
> First of all, most stains do not contain manganese. And of course,
> one of the primary REASONS they make fritted materials is to
> eliminate toxicity resulting from soluble compounds in raw
> materials. That would not be a concern with most of the coloring oxides we
> work with, because they are benign in skin contact, but the whole point is
> that any ceramic material in a frit is sealed in a glass, and while you
> certainly have to worry about toxicity in inhalation (silica dust), you do not
> have to worry about skin absorption risks.
> ...
I suffer from eczema, and my hands and are usually covered with cuts. (Please
don't tell me about cures for eczema. I have tried everything, and decided that
the best thing to do is to learn to live with it.)
I was wondering if there is an increased risk of exposure through the cuts in my
fingers even though the materials are fritted.
As far as I know, I have taken all of these materials out of my studio, and I
now wear gloves whenever I am glazing. However, in the past I didn't realize
the dangers involved in using these materials.
Brenda.
Dannon Rhudy on thu 4 apr 02
..... seem to
>be a lot of speckled clays in the catalogues .
>imagining there are manganese fumes ...
...wondering how much, ...
>Any ideas how paranoid we should be?.......
You shouldn't be paranoid at all. Doesn't help a thing.
You SHOULD take care not to be around the kiln when it
is firing, which is to say that you do not want to breathe
in those fumes, or have them drifting through the house,
etc. Breathing stuff in is a most efficient way to
get lots of it into your body. A little manganese
over a long period of time, or a lot of manganese over
a short period - not much to choose, there, either.
So an occasional manganese glaze or a manganese speckled
clay ...maybe the same, given time. Of course, it seems
not a good idea to hang about breathing kiln fumes of
any kind on a regular basis. My kilns are all outside,
and I stay on the upwind side when I'm firing/checking/
adjusting. I don't use manganese, but there's other
stuff to consider.
I've seen three cases, personally, of probable manganese
poisoning. I don't ever want to go there.
regards
Dannon Rhudy
Ababi on thu 4 apr 02
It worries me too, but I am think I exaggerate. I know there is some
dust in it but I mix it into wet slurry with a mixer and all there is
0.2%, yet I would like to hear more, I think Edouard Bastarache gave
kind of answer. My next project: To add granular manganese to Calico of
Laguna and to paint some of it with black iron oxide plus granular
manganese. I tried to go around ( read my last Pyrite letters) but did
not succeed yet. I want to "beat" the very expensive Amaco K-48 (?) I
think.
You can see in my stoneware page: I called it wild dish it is made out
of white plus terra cotta claybody with 0.3% granular manganese, too
much!
sincerely
Ababi Sharon
Kibbutz Shoval- Israel
Glaze addict
ababisha@shoval.org.il
http://members4.clubphoto.com/ababi306910/
http://www.milkywayceramics.com/cgallery/asharon.htm
http://www.israelceramics.org/
---------- Original Message ----------
>Do you think Cone 6 speckled clay with granular manganese would
>give off as many fumes as a heavy manganese glaze? There seem to
>be a lot of speckled clays in the catalogues these days. I'm
>imagining there are manganese fumes in the bisk and glaze
>firings of these manganese bearing clays even if you use safe
>glazes. But I'm wondering how much, since the manganese is
>dispersed in the granular form throughout the clay.
>Any ideas how paranoid we should be?
>Jennifer
>vince pitelka wrote:
>>
>> When I was doing research for my book, I communicated a lot with
>Edouard
>> Bastarache, who is a frequent contributor to this list and is an MD
>and a
>> toxicologist. I do not know if he is monitoring it right now. He
>assured
>> me that the standard ceramic oxides are safe for skin contact and
>cannot be
>> absorbed through the skin. The toxicity problems exist in breathing
>the
>> dust, and in the firing, some oxides (especially manganese) give off
>highly
>> toxic
>> fumes.
>>
>~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*~*
>Jennifer Boyer mailto:jboyer@adelphia.net
>Thistle Hill Pottery
>95 Powder Horn Glen Rd
>Montpelier, VT 05602 USA
>802-223-8926
>http://www.thistlehillpottery.com/
>Never pass on an email warning without checking out this site
>for web hoaxes and junk:
>http://urbanlegends.about.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.
Nevin Murtha on thu 4 apr 02
I consulted some references I have and a friend who is a Certified
Industrial Hygienist. Neither of us could either find any information
suggesting MgO2 would be a particular health threat or think of a reaction
in which it would likly couse a problem. in the presence of water if forms
magnesium hydroxide which is used as as a stomach ache and diariah remedy
(milk of magnesia). I suggest you check the MSDS from your supplier.
Nevin Murtha
n.murtha@worldnet.att.net
-----Original Message-----
From: Axner Co.
To: CLAYART@LSV.CERAMICS.ORG
Date: Wednesday, April 03, 2002 11:57 AM
Subject: Black Clay Safety Inquiry
>Dear Clay Art Members,
>
>I would like to get some information from you with regards to possible
>health risks associated with making and using black clay.
>
>Twenty-five years ago, I used black clay in my own pottery production and
>found it to be beautiful. I had it custom made for me from my own
>formulations (this was way before I started making clay). I know a
>number of people who use black clay now and make beautiful pots with it.
>We at Axner have the capability of making black clay now but I have
>refused to so due to the fact that I am of the impression that black clay
>bodies can pose a serious health risk, depending on how they are made.
>In particular, I am concerned with the use of Magnesium Dioxide. I know
>one potter and heard of a number of others who have had very serious
>health problems that were said to be due to exposure to Magnesium
>Dioxide. I would like to know if anyone has more information as to the
>accuracy of this and I would like to know if anyone else knows of people
>who have had problems due to exposures to this or other chemicals. I
>have heard things in an antidotal fashion, and I am interested in getting
>more antidotal information, but I am far more interested in getting some
>facts that are based on citeable research.
>
>By the way, we offer a series of colored clays (including black) in small
>quantities. They are made with Mason Stains in a way that I believe are
>not a health hazard. It is too expensive to make clay in this fashion
>for anything other than very small works.
>
>Howard Axner
>
>___________________________________________________________________________
___
>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.
>
potterybydai on thu 4 apr 02
Nevin, it's manganese we're worried about, not magnesium!
Dai in Kelowna, BC
potterybydai@shaw.ca
Life is 10% what happens to you, and 90% how you
respond to it.
----- Original Message -----
From: "Nevin Murtha"
To:
Sent: Thursday, April 04, 2002 12:47 PM
Subject: Re: [CLAYART] Black Clay Safety Inquiry
> I consulted some references I have and a friend who is a Certified
> Industrial Hygienist. Neither of us could either find any information
> suggesting MgO2 would be a particular health threat or think of a reaction
> in which it would likly couse a problem. in the presence of water if
forms
> magnesium hydroxide which is used as as a stomach ache and diariah remedy
> (milk of magnesia). I suggest you check the MSDS from your supplier.
>
> Nevin Murtha
> n.murtha@worldnet.att.net
Ron Roy on fri 5 apr 02
I think what Jennifer is saying here is useful information. Some colours do
contain Manganese - friting does not render them safe - see the reasons for
that in our book - loading up a glaze with oxides is a sure way to
destabilize them. This means - if the dust is inhaled they can break down
in the lungs.
Also - when fired - the fumes are still be a hazard.
I see a very real reason for potters to be aware of such possibilities -
particularly when kilns are being fired in the same building where others
are living - particularly children. It is one thing to take chances with
your own health but it is not alright to compromise others.
We should know which oxides are or can be a problem so we can make choices
depending on what we feel is the right thing to do. The experts disagree -
continually - and in most cased the allowable limits go down - not up.
Knowing our materials is never a bad idea - even if it sometimes scares us.
RR
>We see a lot of well-meaning but very careless and irresponsible "advice" on
>Clayart concerning toxicity issues. It does no good to be an alarmist about
>these things unless your facts are solid. Either take the time to do your
>research, or else DO NOT post "warnings" about supposedly toxic materials.
>
>Jennifer wrote:
>> (By the way, most stains contain manganese so that does not make them any
>> safer than using manganese directly.)
>
>The above is a good example. First of all, most stains do not contain
>manganese. And of course, one of the primary REASONS they make fritted
>materials is to eliminate toxicity resulting from soluble compounds in raw
>materials. That would not be a concern with most of the coloring oxides we
>work with, because they are benign in skin contact, but the whole point is
>that any ceramic material in a frit is sealed in a glass, and while you
>certainly have to worry about toxicity in
>inhalation (silica dust), you do not have to worry about skin absorption
>risks.
Ron Roy
RR #4
15084 Little Lake Road
Brighton
Ontario
Canada - K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
bnsaijim on fri 5 apr 02
<Dai in Kelowna, BC
potterybydai@shaw.ca
> I consulted some references I have and a friend who is a
Certified
> Industrial Hygienist
There's them CIH's for ya... For what it's worth,
Certifications are a good indicator of one's testing
ability... which I think is covered in some other threads...
MSDS are okay but they're written by lawyers and provide no
real sense of true risk. Try looking for one on saline
solution sometime for a good laugh...
I assume the original post was asking for info on manganese
compounds...
Here's some down to earth info on MANGANESE.
For the whole read,
http://www.atsdr.cdc.gov/toxprofiles/phs151.html
In summary,
"...Manganese miners or steel workers exposed to high levels
of manganese dust in air may have mental and emotional
disturbances, and their body movements may become slow and
clumsy. This combination of symptoms is a disease called
=91manganism.=92
A recent study showed that people who inhaled manganese from
the air and who had high levels of manganese in their blood
showed signs of neurological problems that were similar to
those reported in occupationally-exposed persons. The
neurological problems were most significant in the people
aged 50 years and older. "
This info comes from a good general source. Just search for
your substance of concern...
http://www.atsdr.cdc.gov/
BTW, I feel free to pick on CIH's as I R 1 2. If anyone on
List has safety concerns or questions LMK, I may be able to
help with info. Been an IH for 12 years...
Jim Stone, MSPH, CSP, CIH,
(and working on a PhD in Environmental Toxicology...) Time
for a bigger business card.
TX
vince pitelka on fri 5 apr 02
> I think what Jennifer is saying here is useful information. Some colours
do
> contain Manganese - friting does not render them safe - see the reasons
for
> that in our book - loading up a glaze with oxides is a sure way to
> destabilize them. This means - if the dust is inhaled they can break down
> in the lungs.
Ron -
If fritting them does not make them safe, them by all means tell us why. Do
not tell us to "see the reasons in our book." You are talking about
people's safety. From everything I know, fritting them DOES make them safe
in the raw fritted materials and in glaze application. Of course there is
still a danger from fumes in firing, and from possible toxic materials
release in the fired glaze. And frits are always dangerous in inhalation,
because they are powdered glass.
I am completely in support of maintaining respect for you and your book when
it comes to glaze recipes and other information concerning glaze application
and firing processes, but when it comes to safety issues, do not make people
consult your book in order to find the needed information.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@dtccom.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
Ron Roy on sat 6 apr 02
Hi Vince,
Can't do it in a post - we wrote the book to explain about solubility - if
you want to understand why some frits will not be stable you are going to
have to read it - most of the book is an explanation of why some glasses
are stable and others not.
One of the rules for making stable glass is not overloading with colouring
oxides. Stains are loaded with colouring oxides and will leach when exposed
to acids which means - if they are inhaled they will break down in the
lungs. There may be exceptions to this - like maybe the encapsulated stains
but you must also understand - some of the crystals are not complete and
there still might be a risk.
Understanding glaze solubility is an important part of our craft - I urge
everyone to learn as much as they can about this - our book is written in a
way that makes it understandable - but you do have to read it - I don't
know of any other way to do it unless you want to do your own research.
RR.
>> I think what Jennifer is saying here is useful information. Some colours
>do
>> contain Manganese - friting does not render them safe - see the reasons
>for
>> that in our book - loading up a glaze with oxides is a sure way to
>> destabilize them. This means - if the dust is inhaled they can break down
>> in the lungs.
>
>Ron -
>If fritting them does not make them safe, them by all means tell us why. Do
>not tell us to "see the reasons in our book." You are talking about
>people's safety. From everything I know, fritting them DOES make them safe
>in the raw fritted materials and in glaze application. Of course there is
>still a danger from fumes in firing, and from possible toxic materials
>release in the fired glaze. And frits are always dangerous in inhalation,
>because they are powdered glass.
>
>I am completely in support of maintaining respect for you and your book when
>it comes to glaze recipes and other information concerning glaze application
>and firing processes, but when it comes to safety issues, do not make people
>consult your book in order to find the needed information.
>Best wishes -
>- Vince
Ron Roy
RR #4
15084 Little Lake Road
Brighton
Ontario
Canada - K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Edouard Bastarache on sat 6 apr 02
Hello Ron,
"Stains are loaded with colouring oxides and will leach when exposed
to acids which means - if they are inhaled they will break down in the
lungs.
RR."
Are stains water-soluble or acid- soluble or both?
Because there is no acid in the lungs, if it was so,
we would not be here to read Clayart.
The lungs are not the stomach!!!
There are definite clinical entities related to
inhalation of acids, among which death.
Later,
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
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