Charles Wike on mon 7 feb 00
I recieved a nice message from Christine at Kickwheel and she mentioned to
me that I was incorrect in thinking that there is lots of manganese in their
Black Raven stoneware body. She told me that it has less than 1%. I am glad
to hear that and just wanted to set the record straight. I didn't want any
one to stop using the clay or avoid it because of my mis-information!
Thanks again to Christine & Kickwheel for helping me out!
Celia
Chris Schafale on tue 8 feb 00
Umm, did she tell you what it is that makes it black, if not
manganese?? I'm betting that it does actually have a lot, but in the
form of Blackbird/Barnard or some other clay, rather than from a jar
labelled "manganese".
Chris
> ----------------------------Original message----------------------------
> I recieved a nice message from Christine at Kickwheel and she mentioned to
> me that I was incorrect in thinking that there is lots of manganese in their
> Black Raven stoneware body. She told me that it has less than 1%. I am glad
> to hear that and just wanted to set the record straight. I didn't want any
> one to stop using the clay or avoid it because of my mis-information!
>
> Thanks again to Christine & Kickwheel for helping me out!
>
> Celia
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
http://www.angelfire.com/nc2/candle (work in progress)
Vince Pitelka on wed 9 feb 00
At 02:02 PM 2/8/00 EST, you wrote:
>----------------------------Original message----------------------------
>Umm, did she tell you what it is that makes it black, if not
>manganese?? I'm betting that it does actually have a lot, but in the
>form of Blackbird/Barnard or some other clay, rather than from a jar
>labelled "manganese".
If you are concerned about manganese toxicity, most toxicologists, including
our own Dr. Edouarde Bastarouche, agree that powdered or granular manganese
cannot be absorbed through the skin, and offers no danger in claybodies,
other than the normal warnings against breathing the dry dust.
Best wishes -
- Vince
Vince Pitelka
Home - vpitelka@DeKalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Edouard Bastarache on thu 10 feb 00
------------------
Hello all,
here is the last version of my text on manganese:
Manganese =26 inorganic compounds
Manganese compounds used by potters are inorganic , like manganese dioxide,
oxide
and manganese carbonate=3B they do not penetrate the body via the skin as
compared to some organic compounds.
Metallic applications account for most manganese consumption, with about
90=25
used in steelmaking.
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.
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 (10=25). Very few poisonings =
have
occured after ingestion.
Tricarbonyls (organic) of manganese can be absorbed by the skin.
The primary target organs of manganese toxicity are the brain and the lungs.
1-Neurological symptoms (chronic manganese poisoning) are caused by
inhalation of fumes or dusts 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.
The symptoms may simulate progressive bulbar paralysis, postencephalitic
Parkinsonism, multiple sclerosis, amyotrophic lateral sclerosis and
progressive lenticular degeneration(Wilson's disease).
2-Toxicity to the lungs is manifested as increased susceptibility to
bronchitis or, in more severe cases, manganic pneumonia.
According to Robert R. Lauwerys ( probably the best occupational
toxicologist in the world) in =22Toxicologie Industrielle et Intoxications
Professionnelles, 1999=22, the best way to diagnose, at an early
stage, manganese intoxication is neurological examination.
A standardized questionnaire of neurological symptoms is helpful.
Workers exposed to manganese should have a medical examination
every 3 to 6 months (Shunk=3B Tanaka et 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 for proposing a
a blood standard for manganese.
Tanaka =26 Lieben however observed a correlation between the urinary
excretion and the intensity of the exposure and japanese authors
suggested that manganese excretion higher than 40-50 micrograms/liter
corresponds to an exposure where lesions can occur (Horiuchi =26 al.) .
Best thing to do is to treat a patient not a lab test (an old saying in
medicine).
I have heard of 2 cases of Parkinson =96like syndrome among unskilled =
workers
making clays and glazes for a local pottery supplies store (Montreal) that
happened in the 70's and 80's before Quebec passed its laws in Occupational
Health and Safety (I was personnally involved in this process).
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. It certainly depends also on the amount used over a given period
of time in clays and glazes.
In the wet state, as in moist clays and glazes, these compounds are
certainly much less hazardous than as dust.Factories can afford the
monitoring of manganese exposure but it is not the same for artists and
craftpersons.
So good house keeping of your studio is important. Avoidance of processes
generating unnecessary dust is also important and the wearing of an approved
dust mask when the exposure seems hazardous.
REFERENCES :
1-Occupational Medicine, Carl Zenz, last edition.
2-Occupational =26 Environmental Medicine, Joseph LaDou, last edition.
3-Chemical Hazards of the Workplace, Proctor =26 Hughes, last edition.
4-Industrial Chemical Exposure, Lauwerys =26 Hoet, last edition.
5-Toxicologie Industrielle et intoxications professionnelles, Lauwerys
Robert,R.1999
Later
Edouard Bastarache
Dans / In =22La Belle Province=22
edouardb=40sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/=7Eedouardb/
-----Message d'origine-----
De : Vince Pitelka =3Cvpitelka=40DeKalb.net=3E
=C0 : CLAYART=40LSV.UKY.EDU =3CCLAYART=40LSV.UKY.EDU=3E
Date : 9 f=E9vrier, 2000 14:08
Objet : Re: Black Raven
----------------------------Original message----------------------------
At 02:02 PM 2/8/00 EST, you wrote:
=3E----------------------------Original message----------------------------
=3EUmm, did she tell you what it is that makes it black, if not
=3Emanganese?? I'm betting that it does actually have a lot, but in the
=3Eform of Blackbird/Barnard or some other clay, rather than from a jar
=3Elabelled =22manganese=22.
If you are concerned about manganese toxicity, most toxicologists, including
our own Dr. Edouarde Bastarouche, agree that powdered or granular manganese
cannot be absorbed through the skin, and offers no danger in claybodies,
other than the normal warnings against breathing the dry dust.
Best wishes -
- Vince
Vince Pitelka
Home - vpitelka=40DeKalb.net
615/597-5376
Work - wpitelka=40tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Veena Raghavan on thu 10 feb 00
Message text written by Ceramic Arts Discussion List
>If you are concerned about manganese toxicity, most toxicologists,
including
our own Dr. Edouarde Bastarouche, agree that powdered or granular manganese
cannot be absorbed through the skin, and offers no danger in claybodies,
other than the normal warnings against breathing the dry dust.
<
Vince,
If a clay has a high manganese level, is it still alright for
functional ware that will be used for food and drink. I would like to get a
black clay but have always hesitated because of this.
Thanks in advance.
Veena
Veena Raghavan
75124.2520@compuserve.com
Karin Hurt on thu 10 feb 00
Midsouth in Nashville has a black clay "Cassius Clay", I was told it's
dangerous in dry form (dust) because of the Manganese. It's a beautiful but
temperamental clay, reaches its blackest stage at Oxidation cone 5. I
experienced lots of warping and eventually dropped it. It's nearly as smooth
as porcelain and quit beautiful.
ACTSNYC@cs.com on fri 11 feb 00
>
> >Date: Thu, 10 Feb 2000 14:50:59 EST
> >Sender: Ceramic Arts Discussion List
> >From: Edouard Bastarache
> >Subject: Re: Black Raven
> >----------------------------Original message----------------------------
> >Hello all,
> >here is the last version of my text on manganese:
> >Manganese =26 inorganic compounds
> >Manganese compounds used by potters are inorganic , like manganese
dioxide,
> >oxide
> >and manganese carbonate=3B they do not penetrate the body via the skin as
> >compared to some organic compounds. <
SNIP AND FAST FORWARD TO:
>-----Message d'origine-----
> >De : Vince Pitelka =3Cvpitelka=40DeKalb.net=3E
> >=C0 : CLAYART=40LSV.UKY.EDU =3CCLAYART=40LSV.UKY.EDU=3E
> >Date : 9 f=E9vrier, 2000 14:08
> >Objet : Re: Black Raven
> >=3E----------------------------Original
message----------------------------
> >If you are concerned about manganese toxicity, most toxicologists,
> including
> >our own Dr. Edouarde Bastarouche, agree that powdered or granular
manganese
> >cannot be absorbed through the skin, and offers no danger in claybodies,
> >other than the normal warnings against breathing the dry dust.
> >Best wishes -
> >- Vince
> >615/597-5376
> >Work - wpitelka=40tntech.edu
> >615/597-6801 ext. 111, fax 615/597-6803
> >Appalachian Center for Crafts
> >Tennessee Technological University
> >1560 Craft Center Drive, Smithville TN 37166
>
Isn't it amazing how the doctor's very correct statement about inorganic
manganese compounds that:
"....they do not penetrate the body via the skin as compared to some organic
compounds.... "
in the hands of a seller of manganese clays became:
"...powdered or granular manganese cannot be absorbed through the skin..."
I have not read every study of manganese compounds, but unless a specific
study has been done on skin absorption, the statement needs to be
conservative. For example, almost every text says that lead doesn't skin
absorb. And then in about 1990, the first study ever done on skin
absorption of finely powdered lead metal and lead oxide powder showed that it
does absorb!
Most metal compounds have never been tested for skin absorption directly. So
the doctor's more conservative statement is the one by which you should be
guided. And while clearly, it doesn't just soak through the skin rapidly as
the organic manganese compounds do, there probably is no actual study of
manganese dioxide or manganese carbonate skin absorption. If there is one, I
would love to know about it.
All this aside, obviously the major danger is by inhalation. And the clay
dust in your pottery will contain a component of manganese if you use
manganese clays. Anyone who has ever worked with granular manganese knows
that there is a lot of fine stuff in the product as well. That's the primary
hazard. Keep the joint clean.
Monona Rossol
ACTS
181 Thompson St., # 23
NYC NY 10012-2586 212/777-0062
ACTSNYC@cs.com
Edouard Bastarache on sat 12 feb 00
------------------
Hello all,
in Hazardous Materials Toxicology by Sullivan =26 Krieger it is said:
=22 There does not seem to be significant dermal absorption, altough
contact dermititis has been reported=22(page 897, last edition).
Lauwerys in =22Toxicologie Industrielle et Intoxications professionnelles=22
says:=22En milieu industriel, la principale voie d'entr=E9e du mangan=E8se
dans l'organisme est la voie pulmonaire, la voie digestive ne jouant
qu'un r=F4le secondaire=22.Translated to english by =22dear ol' me=22 it =
means:
=22 In the industrial setting, the main route of entry into the body is the
pulmonary
one, the digestive one playing only a secondary role=22.There is no mention
in his 1999 edition of a skin route of entry.
So, make your pick=21=21=21
Later,
Edouard Bastarache
Dans / In =22La Belle Province=22
edouardb=40sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/=7Eedouardb/
-----Message d'origine-----
De : ACTSNYC=40cs.com =3CACTSNYC=40cs.com=3E
=C0 : CLAYART=40LSV.UKY.EDU =3CCLAYART=40LSV.UKY.EDU=3E
Date : 11 f=E9vrier, 2000 14:10
Objet : Re: Black Raven
=3E----------------------------Original message----------------------------
=3E
=3E=3E
=3E=3E =3EDate: Thu, 10 Feb 2000 14:50:59 EST
=3E=3E =3ESender: Ceramic Arts Discussion List =3CCLAYART=40LSV.UKY.EDU=3E
=3E=3E =3EFrom: Edouard Bastarache =3Cedouardb=40sorel-tracy.qc.ca=3E
=3E=3E =3ESubject: Re: Black Raven
=3E=3E =3E----------------------------Original
message----------------------------
=3E=3E =3EHello all,
=3E=3E =3Ehere is the last version of my text on manganese:
=3E=3E =3EManganese =3D26 inorganic compounds
=3E=3E =3EManganese compounds used by potters are inorganic , like =
manganese
=3Edioxide,
=3E=3E =3Eoxide
=3E=3E =3Eand manganese carbonate=3D3B they do not penetrate the body via =
the skin
as
=3E=3E =3Ecompared to some organic compounds. =3C
=3E
=3ESNIP AND FAST FORWARD TO:
=3E
=3E =3E-----Message d'origine-----
=3E=3E =3EDe : Vince Pitelka =3D3Cvpitelka=3D40DeKalb.net=3D3E
=3E=3E =3E=3DC0 : CLAYART=3D40LSV.UKY.EDU =3D3CCLAYART=3D40LSV.UKY.EDU=3D3E
=3E=3E =3EDate : 9 f=3DE9vrier, 2000 14:08
=3E=3E =3EObjet : Re: Black Raven
=3E=3E =3E=3D3E----------------------------Original
=3Emessage----------------------------
=3E=3E =3EIf you are concerned about manganese toxicity, most =
toxicologists,
=3E=3E including
=3E=3E =3Eour own Dr. Edouarde Bastarouche, agree that powdered or granular
=3Emanganese
=3E=3E =3Ecannot be absorbed through the skin, and offers no danger in
claybodies,
=3E=3E =3Eother than the normal warnings against breathing the dry dust.
=3E=3E =3EBest wishes -
=3E=3E =3E- Vince
=3E=3E =3E615/597-5376
=3E=3E =3EWork - wpitelka=3D40tntech.edu
=3E=3E =3E615/597-6801 ext. 111, fax 615/597-6803
=3E=3E =3EAppalachian Center for Crafts
=3E=3E =3ETennessee Technological University
=3E=3E =3E1560 Craft Center Drive, Smithville TN 37166
=3E=3E
=3EIsn't it amazing how the doctor's very correct statement about inorganic
=3Emanganese compounds that:
=3E
=3E=22....they do not penetrate the body via the skin as compared to some
organic
=3Ecompounds.... =22
=3E
=3Ein the hands of a seller of manganese clays became:
=3E
=3E=22...powdered or granular manganese cannot be absorbed through the =
skin...=22
=3E
=3EI have not read every study of manganese compounds, but unless a specific
=3Estudy has been done on skin absorption, the statement needs to be
=3Econservative. For example, almost every text says that lead doesn't skin
=3Eabsorb. And then in about 1990, the first study ever done on skin
=3Eabsorption of finely powdered lead metal and lead oxide powder showed =
that
it
=3Edoes absorb=21
=3E
=3E
=3EMost metal compounds have never been tested for skin absorption directly.
So
=3Ethe doctor's more conservative statement is the one by which you should =
be
=3Eguided. And while clearly, it doesn't just soak through the skin rapidly
as
=3Ethe organic manganese compounds do, there probably is no actual study of
=3Emanganese dioxide or manganese carbonate skin absorption. If there is =
one,
I
=3Ewould love to know about it.
=3E
=3E
=3EAll this aside, obviously the major danger is by inhalation. And the =
clay
=3Edust in your pottery will contain a component of manganese if you use
=3Emanganese clays. Anyone who has ever worked with granular manganese =
knows
=3Ethat there is a lot of fine stuff in the product as well. That's the
primary
=3Ehazard. Keep the joint clean.
=3E
=3E
=3EMonona Rossol
=3EACTS
=3E181 Thompson St., =23 23
=3ENYC NY 10012-2586 212/777-0062
=3E
=3EACTSNYC=40cs.com
Kickwheel@aol.com on mon 14 feb 00
------------------
Although I enjoy the publicity for our Black Raven clay, I fee I must =
set
the record straight on its manganese content. Black Raven=92s dominant =
colorant
is several irons that are blended together. It does not have Barnard Clay
mixed into it, as someone thought it might. It has less than 1 percent
manganese. If you look at it wet and compare it to, say Cassius Clay from
another manufacturer, you will see that Black Raven is a deep reddish brown
color, not black. It does not become black until it is fired to cone six or
seven. It is beautiful, but, because of its heavy iron content, it can be
persnickety if it is not bisqued properly.
Good housekeeping is good advise for all clay materials and has been
strongly advised by our family and employees for the last 26 years of
business.
I believe that it is always wise to arm yourself with all the =
information
available about all the things around us and consider this an excellent and
important discussion.
Christine
Kickwheel Pottery Supply, Inc.
Atlanta, GA
www.kickwheel.com
Karin Hurt on tue 15 feb 00
I've worked with your Black Raven and found it wonderful to work with. At
cone 6 oxidation, the color came close to being black. Cassius clay does not
accept glazes well at all.
Gary Elfring on mon 21 feb 00
At 12:00 AM 2/20/00 -0500, you wrote:
>And there is
>no data on manganese skin absorption to evaluate, just as there was no data
>on lead absorption until a few years ago. Now we know lead absorbs. Maybe
>manganese does to. I really don't know. And neither does the authority you
>quote which is clear from his own words.
I don't know why these doctors education was so lacking, but *anyone* who
reads history knows that lead can be easily absorbed through the skin!
There are many histories of queen Elizabeth's reign (England) and all state
that the craze she started for white faces lead to numerous deaths from
lead poisoning! (They used lead based white face powder.)
Elfring Fonts, Inc Bar Codes, MICR, and decorative fonts for Windows
http://www.elfring.com
CNW on tue 22 feb 00
Okay- since I started this thread....
It has been clarified by the supplier that Black Raven contains LESS than 1%
manganese. So please use another heading for your manganese posts. I would
hate for this clay to be maligned for my mistake.
So please if you want to talk about manganese please find another heading.
Thanks.
Celia in NC-feeling bad about my mistake.
cwike@conninc.com
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