Mary Ernst on thu 17 jun 99
I know this may seem a redundant topic but I still don't quite get it. I
read that you can potentially get manganese poisoning from glaze
leaching, from inhallation (fumes. clay dust with manganese particles),
from breathing kiln fumes, from ingestion. I had one instructor who was
adament that claybodies with manganese should not be used for functional
ware yet another instructor has used manganese frequently in glazes and
says if the integrity of the glaze is good there is not a problem. I am
trying hard to maintain safe clay practices but I really want to
understand why I am doing what I am doing. I like the look of speckled
clay bodies and I like the richness of the glazes over these bodies, but
frankly I have quit using manganese all together both in my glazes and
in clays. Am I being paranoid? Is manganese more of an issue in clay
body or glaze or both? Perhaps Ron Roy or Monona Rossoll or others could
help me out. My fellow classmates think I'm a bit nuts. Thanks in
advance.
Mary in Charleston
John Hesselberth on fri 18 jun 99
Mary Ernst wrote:
>----------------------------Original message----------------------------
>I know this may seem a redundant topic but I still don't quite get it. I
>read that you can potentially get manganese poisoning from glaze
>leaching, from inhallation (fumes. clay dust with manganese particles),
>from breathing kiln fumes, from ingestion. I had one instructor who was
>adament that claybodies with manganese should not be used for functional
>ware yet another instructor has used manganese frequently in glazes and
>says if the integrity of the glaze is good there is not a problem. I am
>trying hard to maintain safe clay practices but I really want to
>understand why I am doing what I am doing. I like the look of speckled
>clay bodies and I like the richness of the glazes over these bodies, but
>frankly I have quit using manganese all together both in my glazes and
>in clays. Am I being paranoid? Is manganese more of an issue in clay
>body or glaze or both? Perhaps Ron Roy or Monona Rossoll or others could
>help me out. My fellow classmates think I'm a bit nuts. Thanks in
>advance.
>
>Mary in Charleston
Hi Mary,
I'll take a crack at part of your question. Manganese can be used safely
in glazes if the glaze is durable to leaching. Unfortunately, the only
way to know is to have it tested given our current state of knowledge.
You cannot predict this from limit formulas; although I believe a glaze
within limits is more likely to be durable to leaching than one that is
outside of limits--but being in limits is no guarantee. For instructions
on how to have glazes tested professionally at very modest cost go to
http://www.frogpondpottery.com/glazetest.html If you get a result less
than, say, 2 mg/l you are certainly in the safe range (There are
currently no drinking water standards for manganese; however it is my
understanding that Canada has proposed a 2 mg/l limit. If it is above
2.0 you will have to use your own judgment because there is simply no
hard data available. Actually, though, we ingest quite a bit of
manganese in our every day diets--at least those of us who eat grains,
eat potatoes or drink tea. Daily manganese intake via food has been
estimated to be from 2-14 mg/ day in various parts of the world.
I personally will use manganese in glazes, but not before I test the
glaze for leaching.
As to manganese fumes or dust, these are nasty things. I'll leave it to
Monona, though, to tell you how nasty they are. From my perspective, I
make sure I wear a HEPA mask and have a well ventilated kiln when I
mix/handle/fire manganese-containing glazes. I also am not the person to
try to answer regarding manganese use in speckled clay bodies.
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"It is time for potters to claim their proper field. Pottery in its pure
form relies neither on sculptural additions nor on pictorial decorations.
but on the counterpoint of form, design, colour, texture and the quality
of the material, all directed to a function." Michael Cardew in "Pioneer
Pottery"
Ron Roy on sat 19 jun 99
There are now cases of potters who have manganese poisoning - and it is now
being added to gasoline instead of lead.
I am not an expert but it seems to me the main danger is to the maker -
someone - on this list explained that ingesting Manganese is not a big
problem - I don't know if that is true and would like to be sure of it - so
if anyone knows about the ingestion issue please let us know again.
On the other hand - breathing MnO2 dust is not recommended - and the fumes
from firing it really are a danger. I don't think granular manganese is
anywhere near the danger of the dust - simply because it can't stay
suspended in air. If there is dust with the granular then perhaps some
washing is in order.
Is there significant danger from the granular in bodies - I don't think
it's a big problem - but it would depend on how the kiln is vented and
where the vented fumes are going I guess.
I happen to know many potters who use granular manganese in their bodies -
for many years - under some less than ideal conditions - the symtoms to
look for are Parkinson like - but if you get that far it's gona get worse -
even if you stop exposure.
RR
>----------------------------Original message----------------------------
>I know this may seem a redundant topic but I still don't quite get it. I
>read that you can potentially get manganese poisoning from glaze
>leaching, from inhallation (fumes. clay dust with manganese particles),
>from breathing kiln fumes, from ingestion. I had one instructor who was
>adament that claybodies with manganese should not be used for functional
>ware yet another instructor has used manganese frequently in glazes and
>says if the integrity of the glaze is good there is not a problem. I am
>trying hard to maintain safe clay practices but I really want to
>understand why I am doing what I am doing. I like the look of speckled
>clay bodies and I like the richness of the glazes over these bodies, but
>frankly I have quit using manganese all together both in my glazes and
>in clays. Am I being paranoid? Is manganese more of an issue in clay
>body or glaze or both? Perhaps Ron Roy or Monona Rossoll or others could
>help me out. My fellow classmates think I'm a bit nuts. Thanks in
>advance.
>
>Mary in Charleston
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
claypots on sun 20 jun 99
-------------------
I read recently where Richard Zakin had manganese poisoning. It was in =
either
Clay Times or Pottery Making Illustrated.
Debra
Edouard Bastarache on sun 20 jun 99
------------------
Hello Ron,
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).
Tricarbonyls (organic) of manganese can be
absorbed by the skin.
The primary target organs of manganese toxicity
are the brain and the lungs.
The toxicity to the brain is manifested as a chronic
disorder of the central nervous system resembling
Parkinsonism.
Toxicity to the lungs is manifested as increased
susceptibility to bronchitis or, in more severe cases,
manganic pneumonia.
The possibilities for monitoring exposure to manganese
by a biological method are still very limited. Most
authors have concluded that there is no direct relation
between manganese concentration in biological
material and the severity of chronic manganese poisoning,
probably because individual susceptibility to the disease
plays an important role.The measurement of manganese
in urine can probably be recommended to confirm the
absorption of manganese, but no biological threshold limit
value can yet be proposed.
Since only inorganic manganese compounds are
used by potters we shall not discuss the organic
ones.
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 or 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.
Later,
Edouard Bastarache
edouardb=40sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/=7Eedouardb/
-----Message d'origine-----
De : Ron Roy =3Cronroy=40total.net=3E
=C0 : CLAYART=40LSV.UKY.EDU =3CCLAYART=40LSV.UKY.EDU=3E
Date : 19 juin, 1999 18:51
Objet : Re: Manganese poisoning - ughh
----------------------------Original message----------------------------
There are now cases of potters who have manganese poisoning - and it is now
being added to gasoline instead of lead.
I am not an expert but it seems to me the main danger is to the maker -
someone - on this list explained that ingesting Manganese is not a big
problem - I don't know if that is true and would like to be sure of it - so
if anyone knows about the ingestion issue please let us know again.
On the other hand - breathing MnO2 dust is not recommended - and the fumes
from firing it really are a danger. I don't think granular manganese is
anywhere near the danger of the dust - simply because it can't stay
suspended in air. If there is dust with the granular then perhaps some
washing is in order.
Is there significant danger from the granular in bodies - I don't think
it's a big problem - but it would depend on how the kiln is vented and
where the vented fumes are going I guess.
I happen to know many potters who use granular manganese in their bodies -
for many years - under some less than ideal conditions - the symtoms to
look for are Parkinson like - but if you get that far it's gona get worse -
even if you stop exposure.
RR
=3E----------------------------Original message----------------------------
=3EI know this may seem a redundant topic but I still don't quite get it. I
=3Eread that you can potentially get manganese poisoning from glaze
=3Eleaching, from inhallation (fumes. clay dust with manganese particles),
=3Efrom breathing kiln fumes, from ingestion. I had one instructor who was
=3Eadament that claybodies with manganese should not be used for functional
=3Eware yet another instructor has used manganese frequently in glazes and
=3Esays if the integrity of the glaze is good there is not a problem. I am
=3Etrying hard to maintain safe clay practices but I really want to
=3Eunderstand why I am doing what I am doing. I like the look of speckled
=3Eclay bodies and I like the richness of the glazes over these bodies, but
=3Efrankly I have quit using manganese all together both in my glazes and
=3Ein clays. Am I being paranoid? Is manganese more of an issue in clay
=3Ebody or glaze or both? Perhaps Ron Roy or Monona Rossoll or others could
=3Ehelp me out. My fellow classmates think I'm a bit nuts. Thanks in
=3Eadvance.
=3E
=3EMary in Charleston
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
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