Kym Valvieja on sat 18 jan 03
Dear Clayart Folks,
I have recently purchased some cone 5 clay from Laguna. It looks and feels
like fudge (sorry can't remember the name). I think I remember hearing about
possible health problems with manganese, can anybody give me info on this
please? Also is it food safe?
Thanks so much,
Kym
Hy Ginsberg on mon 20 jan 03
Kym,
Seeing as none of the experts have seen fit to respond, I will take a shot.
First, if your clay is "fudge" colored, that's not likely to mean that it
contains manganese. Manganese is frequently used to make speckled clay; solid
colors are more likely a result of iron. (Although the manganese speckling
will not show up until the clay is fired...).
If your clay does contain manganese, then in its moist state it is not harmful,
and it is still food safe (I think - experts please correct me if I'm wrong).
The danger with manganese is that it is toxic when inhaled as dust (nervous
system damage, I think - but could, once again, be wrong...). In my book that
makes clays that contain manganese dangerous because there is bound to be dried
bits of clay lying around, which are bound to eventually make dust. Which is
harmful in itself, but you may as well not make it worse and steer clear of
manganese in the first place.
If you're a perfectionist about cleanliness, then perhaps it doesn't matter.
I hope that helps, and if I got any of it wrong, then perhaps those who know
better will see fit to say so...
- Hy Ginsberg
> Dear Clayart Folks,
> I have recently purchased some cone 5 clay from Laguna. It looks and feels
> like fudge (sorry can't remember the name). I think I remember hearing about
> possible health problems with manganese, can anybody give me info on this
> please? Also is it food safe?
> Thanks so much,
> Kym
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Tony Olsen on tue 21 jan 03
Kym:
Found the following on the web: Looks like the fumes and dust are the =
baddies. Keep well ventilated while firing.
Tony (Galveston)
---------------snip-------------- =20
Manganism is a disease caused by excessive exposure to manganese fumes =
or dust. Welders, miners, and others who work with manganese on a daily =
basis are at the highest risk of exposure.=20
Manganism, or manganese poisoning, is often the result of exposure to =
welding fumes. Manganism is characterized by mental difficulties and the =
impairment of motor skills.
Symptoms of Manganism include:
a.. Tremors=20
b.. Awkward gait=20
c.. Abnormal balance=20
d.. Memory loss=20
e.. Impairment of motor skills=20
f.. Slurred speech=20
g.. Lack of facial expression=20
h.. Sleep disorders=20
Welders who have been exposed to welding fumes for many months or years =
should be tested for these conditions.=20
---------------snip--------------
iandol on wed 22 jan 03
Dear Tony Olsen,=20
Interesting about the presence of Manganese in welding fumes. =
Ferro-manganese is a common pre alloy used in eth iron and steel =
industries and was an ingredient in tubular steel electrodes used for =
welding 12% manganese steel. This is an interesting alloy, used as =
armour plating and for the bars of prison cells. Because it work hardens =
rapidly under impact or abrasion it cannot be rolled or drawn, as is the =
steel wire for most structural welding electrodes. But it had an =
advantage. Casting defect in things like Tank Turrets could be filled =
with those tubular electrodes. In addition, no mineral coating was =
needed to shield the arc because the Ferro-manganese acted as a =
de-oxidiser. We made thousands of feet in the welding lab.
I wonder how many of my old pals are suffering the fate you describe, =
working day after day, year in year out with that stuff.
Best regards,
Ivor Lewis.
Ron Roy on wed 22 jan 03
Hi Hy,
Pretty good information - just a couple of additions.
Many clay manufactures make clay with powdered Manganese - usually the
black clays - some have now decided to stop - there is a serious toxicity
issue with manganese - you are right - breathing Manganese as dust is a
risky business. Parkinson type symptoms - and they don't stop when you stop
breathing Manganese - in fact continue to get worse. Not worth the risk as
far as I can see.
Breathing the fumes from firing clays and glazes with Manganese is an even
worse situation. And then there is the residue from those fumes in your
kiln room. The stuff is insidious.
If you only use Manganese occasionally I don't see much of a problem unless
you are unaware of the danger - we all have different levels in us already
so that could be a factor.
Ingestion is not a worry as I understand it.
RR
>Seeing as none of the experts have seen fit to respond, I will take a shot.
>
>First, if your clay is "fudge" colored, that's not likely to mean that it
>contains manganese. Manganese is frequently used to make speckled clay; solid
>colors are more likely a result of iron. (Although the manganese speckling
>will not show up until the clay is fired...).
>
>If your clay does contain manganese, then in its moist state it is not harmful,
>and it is still food safe (I think - experts please correct me if I'm wrong).
>
>The danger with manganese is that it is toxic when inhaled as dust (nervous
>system damage, I think - but could, once again, be wrong...). In my book that
>makes clays that contain manganese dangerous because there is bound to be dried
>bits of clay lying around, which are bound to eventually make dust. Which is
>harmful in itself, but you may as well not make it worse and steer clear of
>manganese in the first place.
>
>If you're a perfectionist about cleanliness, then perhaps it doesn't matter.
>
>I hope that helps, and if I got any of it wrong, then perhaps those who know
>better will see fit to say so...
>
>- Hy Ginsberg
>
>
>> Dear Clayart Folks,
>> I have recently purchased some cone 5 clay from Laguna. It looks and feels
>> like fudge (sorry can't remember the name). I think I remember hearing about
>> possible health problems with manganese, can anybody give me info on this
>> please? Also is it food safe?
>> Thanks so much,
>> Kym
>
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>Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
>http://mailplus.yahoo.com
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Ron Roy
RR#4
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Brighton, Ontario
Canada
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