Bill Merrill on wed 23 sep 09
I just got off the phone with Len from Mason Color. He said he had
received a couple of emails about arsenic in mason stains. He said they
were going to respond to Clayart. He said they looked at some cobalt
stains and the chemistry showed that there were 25 parts per million of
arsenic in the particular stain they looked at. That is very little.
There is arsenic in drinking water, so if potters are worried, don't use
glazes, just make naked pots, forget glazes an d make strong forms that
can stand on their own without makeup.
=3D20
There was a statement about Dave Shaner and it was said in words that
Dave Shaner would have never said "Ya pays ya money & ya takes ya
chances!" Dave for the most part did not use colored slips, but he did
use an Albany slip glaze he called "Maria" and it has nearly 30%
manganese in it. I use his glaze and am very cautious about it. Dave's
gas fired kiln was in his studio, connected to where he worked. He
opened the spy hole many times during a firing and undoubtedly breathed
a lot of manganese fumes over the years of using that glaze. The kiln I
use is outside, under cover with a slatted wood chain link fence. Dave
had about 5 times the normal amount of manganese in his system as a non
potter. Dave had Lou Gerhigs disease or ALS. So, if you have your
kilns inside, vent the area. Build your gas kilns under an open kiln
shed. Use a automotive mask with a fresh air supply. They have a long
hose and a small air pump on the end of the hose. It produces a
positive air flow so you don't breathe the air in front of you. Take
precautions, it is better to error on the safe side. =3D20
John Britt on wed 23 sep 09
Hey Bill,
I found the passage in the Studio Potter, page 36 at the top. (December=3D2=
0=3D
1999, Volume 28, Number 1) This was an article written by David Shaner=3D20=
=3D
and I think it is very illuminating.
"Every time I looked into the peephole, I had fumes coming out. So=3D20
ventilation is important. I did a lot of experimentation with Mason stai=
=3D
ns=3D20
in porcelain clay - pinks and purples and blues. Perhaps I should have=3D20=
=3D
used gloves..."
This article is great because he tell his story and doesn't mince words!
So anyone who hasn't read it...try to get a copy.
John Britt
www.johnbrittpottery.com
Edouard Bastarache on wed 23 sep 09
Bill,
"Dave had Lou Gerhigs disease or ALS."
Experts throughout the world do not recongnise ALS as being related to
manganese exposure.
Fumes, according to exposure limits are 5 times more toxic than respirable
dust.
Good shop ventilation settles de potential problem.
"
AUTHOR: Bob Hirtle; Kay Teschke; Chris van Netten; Michael Brauer
TITLE: Kiln Emissions and Potters' Exposures
SOURCE: American Industrial Hygiene Association Journal v59 no10 p706-14 O =
'98
The magazine publisher is the copyright holder of this article and it is
reproduced with
permission. Further reproduction of this article in violation of the
copyright is prohibited.
ABSTRACT
Some ten thousand British Columbia potters work in small private studios,
cooperative
facilities, educational institutions, or recreation centers. There has been
considerable
concern that this diffuse, largely unregulated activity may involve
exposures to
unacceptable levels of kiln emissions. Pottery kiln emissions were measured
at 50
sites-10 from each of 5 categories: professional studios, recreation
centers,
elementary schools, secondary schools, and colleges. Area monitoring was
done 76 cm
from firing kilns and 1.6 m above the floor to assess breathing zone
concentrations of
nitrogen dioxide, carbon monoxide, sulfur dioxide, fluorides, aldehydes,
aluminum,
antimony, arsenic, barium, beryllium, boron, cadmium, chromium, cobalt,
copper, gold,
iron, lead, lithium, magnesium, manganese, mercury, nickel, selenium,
silver, vanadium,
and zinc. Personal exposures to the same metals were measured at 24 sites.
Almost
all measured values were well below permissible concentrations for British
Columbia
work sites and American Conference of Governmental Industrial Hygienists
(ACGIH)
threshold limit values (TLVs) with the following two exceptions. A single
firing duration
(495 minute) acrolein measurement adjacent to an electric kiln (0.109 ppm)
exceeded
these guidelines. One 15-minute sulfur dioxide measurement collected
adjacent to a
gas kiln (5.7 ppm) exceeded the ACGIH short-term exposure limit. The fact
that
concentrations in small, ventilated kiln rooms ranked among the highest
measured
gives rise to concern that unacceptable levels of contamination may exist
where small
kiln rooms remain unventilated. Custom designed exhaust hoods and industria=
l
heating,
ventilating, and air-conditioning systems were the most effective
ventilation strategies.
Passive diffusion and wall/window fans were least effective.
Gis,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://edouardbastarache.blogspot.com/
http://substitutions.blogspot.com/
http://www.flickr.com/photos/30058682@N00/
http://albertpaintings.blogspot.com/
http://cerampeintures.blogspot.com/
Des & Jan Howard on thu 24 sep 09
Bill
John Britt commented:
>> I remember this same admission in David Shaner's
>> Studio Potter article. He made colored slips
>> the same way knowing the dangers!
I replied:
> "Ya pays ya money & ya takes ya chances!"
In other words, knowing the risks you take the gamble
& will, (or should), accept the consequences.
Des
Bill Merrill wrote:
> There was a statement about Dave Shaner and it was said in words that
> Dave Shaner would have never said "Ya pays ya money & ya takes ya
> chances!" Dave for the most part did not use colored slips, but he did
> use an Albany slip glaze he called "Maria" and it has nearly 30%
> manganese in it. I use his glaze and am very cautious about it.
Excellent idea being cautious. Being paranoid is useless.
--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850
02 6373 6419
www.luepottery.hwy.com.au
-32.656072 149.840624
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