Sojourner Forspam on mon 14 nov 11
bles
I forgot (that happens when I get to rambling instead of staying on track=
=3D
),
re safety -=3D20
Not too long ago I was in the community studio when another potter came i=
=3D
n
who has had several years of working with clay under his belt.
he had recently set up an old electric kiln, sans the electric parts, in =
=3D
his
garage, which he had been planning to do some raku in (not sure if he had=
=3D
already done so, and itself not such a hot idea in an enclosed space,
especially in the face of some of the chemicals used in raku firings).
He started talking about using it for salt firings. When I asked about
venting, he pooh-poohed the idea, stating, "It's just table salt, I put i=
=3D
t
on my fries".
I was aghast. Salt firing releases chlorine gas, and even some acidic
compounds like Hydrochloric Acid. These gases should not even be
contemplated in an enclosed space like a garage. Just a whiff of chlorin=
=3D
e
gas can kill. Get down wind of it and permanent lung damage would be the=
=3D
best outcome you could hope for. With the wind coming from the wrong
direction, opening the garage door could actually make things worse, not =
=3D
better.
According to the Florida State U website=3D20
http://art.fsu.edu/Resources/Environmental-Health-Safety-Guide/Ceramics/S=
=3D
pecial-Processes
Soda & Salt Firing
This process involves throwing salt (sodium chloride) or soda ash (sodium=
=3D
carbonate) into the kiln during a fuel firing. Sodium and chlorine fumes =
=3D
are
produced.
Hazards
* Hydrogen chloride gas is highly toxic. Health effects are similar b=
=3D
ut
more irritating than most other kiln gases. Some local environmental laws=
=3D
ban salt kilns.
* Hydrogen chloride and water forms hydrochloric acid corroding metal=
=3D
fittings in the area.
Precautions
* Salt glazing should only be done outdoors. Kilns should be equipped=
=3D
with chimneys, tall enough to disperse the hydrogen chloride above roof l=
=3D
evels.
* When injecting soda or salt, one should avoid standing in or creati=
=3D
ng
unnecessary fumes.
* All gas piping and metal fixtures should be routinely checked for
corrosion.
The thought of doing this in an old shell of an electric kiln in somebody=
=3D
's
garage scared me, that's all I can say.
Vince Pitelka on tue 15 nov 11
bles
Sojourner Forspam wrote:
"I was aghast. Salt firing releases chlorine gas, and even some acidic
compounds like Hydrochloric Acid. These gases should not even be
contemplated in an enclosed space like a garage. Just a whiff of chlorine
gas can kill. Get down wind of it and permanent lung damage would be the
best outcome you could hope for. With the wind coming from the wrong
direction, opening the garage door could actually make things worse, not
better."
Hi Sojourner -
Your precautions from Florida State University are right on, and notice tha=
t
they do not say anything about chlorine gas. People need to stop
perpetuating the myth that salt firing produces chlorine gas, because it ha=
s
been proven that there is no chlorine gas in salt kiln exhaust. Of course
salt kilns do produce significant quantities of hydrogen chloride gas which
precipitates on metal surfaces (especially in damp weather) as hydrochloric
acid and causes the extreme corrosion we see around salt kilns. People
sometimes make the mistake of saying that salt firing must be
environmentally harmful because of this corrosion, but the corrosion is no
worse than what occurs at the seashore from salt spray. One could certainl=
y
argue that releasing any sort of acid into the atmosphere is harmful, but i=
t
is actually released in very small quantities during a very brief portion o=
f
the firing.
Hydrogen chloride gas in the concentrations present in salt kiln exhaust is
a respiratory irritant if one breaths a significant amount of the fumes, bu=
t
I doubt that it would be considered toxic. In the records from production
salt-firing factories making sewer pipe and other salt-glazed products,
there is no evidence of employees suffering health problems due to exposure
to limited quantities of salt-kiln fumes.
That said, a person would have to be completely crazy to install a salt kil=
n
indoors without extremely sophisticated ventilation equipment that would be
prohibitively expensive for anyone except a university or a commercial
venture. Personally, regardless of how well-funded I was, I would never
place a salt kiln indoors under any circumstances, because there is no way
to capture all of the fumes, so people might be breathing those fumes, and
metal surfaces would begin to corrode badly.
So you were certainly correct in your response to the other potter talking
about salt-firing with a converted toploader in his garage. Very bad idea.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Sojourner Forspam on wed 16 nov 11
bles
--- In clayart@yahoogroups.com, Vince Pitelka wrote:
>=3D20
> Hi Sojourner -
> Your precautions from Florida State University are right on, and notice=
=3D
that
> they do not say anything about chlorine gas.
"Sodium and chlorine fumes are produced."
Possibly I'm blurring the line (if there is one) between chlorine FUMES a=
=3D
nd
chlorine gas. My assumption is that if there isn't chlorine in it, it
wouldn't be chlorine fumes.
The FSU site goes on to state that even an outdoor kiln should be built w=
=3D
ith
a chimney/vent higher than the rooftops of nearby buildings, in order to
give these fumes a chance to dissipate and be less dangerous.
If it corrodes metal, it corrodes human flesh as well, and when you breat=
=3D
he
even small amounts in those amounts become trapped and do not wash away,
blow away, or sink into the ground somehow. What may be considered to be=
=3D
relatively harmless in the open air is not at all so inside your warm and=
=3D
pulsing lungs.
Regardless of how you look at it it's still a bad bad bad BAD thing. The=
=3D
re
are some folks at the studio where I work who occasionally rent a kiln fo=
=3D
r
salt firing from a nearby potter, they're paying 1K per firing (works out=
=3D
to
about $200 to $250 each for 4 or 5 potters per load). The expense alone =
=3D
is
enough to turn me off the idea.
Heck, even assuming you get a "clean" burn that doesn't release any of th=
=3D
e
toxic chemicals we usually think of resulting from a kiln firing, there's=
=3D
still the issue of carbon monoxide, carbon dioxide, and other "usual" but=
=3D
not really very breathable products of burning. I just don't want to be
inside his garage or his house when he's firing, LOL!
Soj
Edouard Bastarache on wed 16 nov 11
bles
Vince and all,
salt-pottery making, industrially or artistically, is not hazardous
according to Brnd Pfankuche, editor of Neue Keramik in Berlin and
international consultant in ceramics.
Using salt in pottery was invented by the Germans.
Naturally never operate a clay shop without proper ventilation,,,
Gis,
Edouard Bastarache
Spertesperantisto
Sorel-Tracy
Quebec
http://www.flickr.com/photos/30058682@N00/
http://edouardbastarache.blogspot.com/
http://edouardbastaracheblogs2.blogspot.com/
http://www.facebook.com/edouard.bastarache
Sojourner Forspam on wed 16 nov 11
bles
I don't know who Brnd Pfankuche is or what Neue Keramik is (I'm guessing
something along the lines of "New Ceramics") and probably he is someone w=
=3D
ho
knows lots and lots more than me about salt firing and many other things =
=3D
as
well.
But anything that releases hydrochloric acid and chlorine fumes is not
something that should be allowed to vent directly into your garage. Or a=
=3D
t
least not MY garage.
Reynolds and Reynolds told us for years that cigarette smoking was not
hazardous, too. Healthful, even.
I'm just sayin'.... Seriously, there is "not hazardous" (which is rarely
true) and "not hazardous when properly done" (which is fairly often true)=
=3D
.=3D20
And no venting, in your garage, just doesn't fall under the first categor=
=3D
y, LOL!
Soj
On Wed, 16 Nov 2011 14:39:06 -0500, Edouard Bastarache =3D
T>
wrote:
>Vince and all,
>
>salt-pottery making, industrially or artistically, is not hazardous
>according to Brnd Pfankuche, editor of Neue Keramik in Berlin and
>international consultant in ceramics.
>Using salt in pottery was invented by the Germans.
>
>Naturally never operate a clay shop without proper ventilation,,,
>
>Gis,
>
>Edouard Bastarache
>Spertesperantisto
>
>Sorel-Tracy
>Quebec
>
>http://www.flickr.com/photos/30058682@N00/
>http://edouardbastarache.blogspot.com/
>http://edouardbastaracheblogs2.blogspot.com/
>http://www.facebook.com/edouard.bastarache
Vince Pitelka on wed 16 nov 11
bles
Sojourner Forspam wrote -
"But anything that releases hydrochloric acid and chlorine fumes is not
something that should be allowed to vent directly into your garage. Or at
least not MY garage."
Sojourner -
Of course it would be insane for anyone to operate such a kiln (or any kiln
without proper ventilation) within a garage. But please stop saying that
salt firings release chlorine fumes, because that is not true. The hydroge=
n
chloride condenses as a weak hydrochloric acid and will cause metal surface=
s
to corrode quickly, but it is not toxic.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Vince Pitelka on wed 16 nov 11
bles
Sojourner Forspam wrote:
"Sodium and chlorine fumes are produced."
"Possibly I'm blurring the line (if there is one) between chlorine FUMES an=
d
chlorine gas. My assumption is that if there isn't chlorine in it, it
wouldn't be chlorine fumes.
Hi Sojourner -
The Florida State guidelines are obviously over the top. There is no
chlorine fumes or chlorine gas. The chlorine released from the sodium
immediately attaches to water molecules that are the natural byproduct of
hydrogen combining with oxygen in the combustion of all hydrocarbon fuels,
so all the chlorine atoms become hydrogen chloride gas, rather than
remaining as free chlorine, which is unstable and wants to combine with
other atoms or molecules. Again, I hate to sound like a broken record, but
there is no chlorine gas or chlorine fumes. Of course it is a good idea fo=
r
any kiln chimney to vent above nearby roofs, but in this case it has to do
with fire safety rather than toxicity.
You wrote:
"If it corrodes metal, it corrodes human flesh as well, and when you breath=
e
even small amounts in those amounts become trapped and do not wash away,
blow away, or sink into the ground somehow. What may be considered to be
relatively harmless in the open air is not at all so inside your warm and
pulsing lungs."
Now if you stop and think about it, I am sure you will agree that the
statement "If it corrodes metal, it corrodes human flesh as well" has no
basis in reality at all. Salt spray at the seashore corrodes metal very
badly, just as much as salt kiln effluent, but does it corrode human flesh?
You wrote:
"Regardless of how you look at it it's still a bad bad bad BAD thing."
If you are referring to the idea of installing an unvented salt kiln inside
a garage, then you are absolutely right. But that would also be true of an=
y
sort of unvented kiln, and most of all any sort of fuel-burning kiln. The
guy who is planning to do this may be headed for the Darwin Awards.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
Steve Mills on thu 17 nov 11
bles
To add to that; once the fumes exit the flue, they are immediately heavily =
d=3D
iluted by the surrounding air, so any corrosive effect tends to be very loc=
a=3D
l.=3D20
Steve M
Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my Ipod touch
On 17 Nov 2011, at 01:06, Vince Pitelka wrote:
Sojourner -
> Of course it would be insane for anyone to operate such a kiln (or any ki=
l=3D
n
> without proper ventilation) within a garage. But please stop saying that
> salt firings release chlorine fumes, because that is not true. The hydro=
g=3D
en
> chloride condenses as a weak hydrochloric acid and will cause metal surfa=
c=3D
es
> to corrode quickly, but it is not toxic.
> - Vince
>=3D20
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpitelka@dtccom.net
> http://iweb.tntech.edu/wpitelka/
Sojourner Forspam on thu 17 nov 11
bles
On Wed, 16 Nov 2011 19:27:01 -0600, Vince Pitelka w=
=3D
rote:
>Sojourner Forspam wrote:
>"Sodium and chlorine fumes are produced."
>"Possibly I'm blurring the line (if there is one) between chlorine FUMES=
=3D
and
>chlorine gas. My assumption is that if there isn't chlorine in it, it
>wouldn't be chlorine fumes.
>
>Hi Sojourner -
>The Florida State guidelines are obviously over the top.=3D20
Not so obvious to me. I have other sources that state this to be true, b=
=3D
ut
frankly I'm too tired to dig them up. I will state that it's also true t=
=3D
hat
these gases are only produced in small quantities that should not be
troublesome to your health or that of your neighbors when properly vented=
=3D
.=3D20=3D20
>chlorine fumes or chlorine gas. The chlorine released from the sodium
>immediately attaches to water molecules that are the natural byproduct o=
=3D
f
>hydrogen combining with oxygen in the combustion of all hydrocarbon fuel=
=3D
s,
>so all the chlorine atoms become hydrogen chloride gas, rather than
>remaining as free chlorine, which is unstable and wants to combine with
>other atoms or molecules. Again, I hate to sound like a broken record, b=
=3D
ut
>there is no chlorine gas or chlorine fumes.=3D20
OSHA disagrees with you.
http://www.osha.gov/SLTC/healthguidelines/hydrogenchloride/recognition.ht=
=3D
ml
"# Hazardous decomposition products: Toxic gases and vapors such as chlor=
=3D
ine
may be released in a fire involving hydrochloric acid."
Kiln - fire - hydrochloric acid, known to be a byproduct of salt firing =3D=
3D=3D
chlorine gas released as vapor/fumes. Admittedly in small quantities of
variable amounts, but still not something you want released into your
garage. Properly VENTED, no big deal - you're right, it does tend to rea=
=3D
ct
quickly with other things, so venting it above rooflines means you've tur=
=3D
ned
a problem into a non-problem. Directly into your garage, at ground level=
=3D
though - in an enclosed space - I'm not taking the chance that the vapors=
=3D
released will react and form a stable non-harmful compound (and I'm sorry=
=3D
,
but hydrochloride gas doesn't qualify as a non-harmful compound) before t=
=3D
hey
make it into my lungs.=3D20=3D20
But lets look at just hydrochloride gas; again, from OSHA:
"Effects on Humans: Hydrogen chloride is irritating and corrosive to the
eyes, skin, and mucous membranes. Exposure to high concentrations can cau=
=3D
se
laryngitis, bronchitis, and pulmonary edema [Rom 1983]. Brief exposures (=
=3D
up
to a few minutes) to concentrations in the range of 1,300 to 2,000 ppm ar=
=3D
e
lethal to humans [Braker and Mossman 1980]. In workers, exposure to 50 to=
=3D
100 ppm for 1 hour was barely tolerable; short exposure to 35 ppm caused
irritation of the throat, and 10 ppm was considered the maximal
concentration allowable for prolonged exposure."
Again, properly vented - no problem, the stuff will dissipate into the sa=
=3D
fe
range long before it reaches ground level (assuming you've vented above t=
=3D
he
roofline and not right next to somebody's open 2nd story window).=3D20
But in your GARAGE.... whole 'nother kettle of fish.
>
>You wrote:
>"If it corrodes metal, it corrodes human flesh as well, and when you bre=
=3D
athe
>even small amounts in those amounts become trapped and do not wash away,=
=3D
>blow away, or sink into the ground somehow. What may be considered to b=
=3D
e
>relatively harmless in the open air is not at all so inside your warm an=
=3D
d
>pulsing lungs."
>
>Now if you stop and think about it, I am sure you will agree that the
>statement "If it corrodes metal, it corrodes human flesh as well" has no=
=3D
>basis in reality at all. Salt spray at the seashore corrodes metal very=
=3D
>badly, just as much as salt kiln effluent, but does it corrode human fle=
=3D
sh?
In point of fact, if you get actual salt in your lungs, do you think that=
=3D
's
a good thing? It WILL, in fact, "corrode" your lungs. Which, last time =
=3D
I
checked, are "flesh". At least mine are. *checks to make sure* Yup, st=
=3D
ill
flesh in there!
But seriously, the compound under discussion there ("it") was not salt, b=
=3D
ut
HYDROCHLORIC ACID. Surely I don't need to convince you that "it" will
"corrode" skin?
*EDIT* Well I went back and checked, and I didn't make that clear in the=
=3D
original posting. I was THINKING "hydrochloric acid" but hadn't made tha=
=3D
t
clear. My bad.
Nevertheless, as I said before: "What may be considered to be relatively=
=3D
harmless in the open air is not at all so inside your warm and pulsing lu=
=3D
ngs."
Salt in and of itself in normal situations is not particularly toxic. Bu=
=3D
t
anything that gets in where it doesn't belong - and it's a whole new ball=
=3D
game. I don't think anyone would deny that we need water to survive - bu=
=3D
t
breathing water will quickly put an end to ALL survival concerns.=3D20
Nevertheless, it isn't salt itself that's at issue here - it's the
byproducts of a salt firing. None of which, as far as I have been able t=
=3D
o
ascertain, are any real problem in a properly vented kiln. But a properl=
=3D
y
vented kiln was not the subject of conversation. At least not MY
conversation, LOL!
>You wrote:
>"Regardless of how you look at it it's still a bad bad bad BAD thing."
>
>If you are referring to the idea of installing an unvented salt kiln ins=
=3D
ide
>a garage, then you are absolutely right. But that would also be true of=
=3D
any
>sort of unvented kiln, and most of all any sort of fuel-burning kiln. T=
=3D
he
>guy who is planning to do this may be headed for the Darwin Awards.
And that is absolutely what I DID say:
"Heck, even assuming you get a "clean" burn that doesn't release any of t=
=3D
he
toxic chemicals we usually think of resulting from a kiln firing, there's=
=3D
still the issue of carbon monoxide, carbon dioxide, and other "usual" but=
=3D
not really very breathable products of burning. I just don't want to be
inside his garage or his house when he's firing, LOL!"
So in case somebody out there still misunderstands my point - I don't thi=
=3D
nk
salt firings are particularly dangerous (or dangerous at all) when done i=
=3D
n a
properly vented kiln.
My issue was the fact that this person was contemplating doing it in an
unvented shell of an old kiln in his garage. Even if he put the thing in=
=3D
his back yard, doing it at ground level leaves something to be desired. =
=3D
And
we're talking a city situation here - not the country where he has severa=
=3D
l
acres for the stuff to dissipate before it gets to his neighbors.
I really think this is a non-issue. Yes, dangerous fumes are released by=
=3D
a
salt firing. (Heck, dangerous fumes are released in just about ANY kind =
=3D
of
firing). No, they're not problematic when done in a properly vented kiln=
=3D
.=3D20
And no, it isn't safe to do this in your garage, unvented, sans any sort =
=3D
of
respiratory protection on top of everything else. That's my only point, =
=3D
and
hopefully not a controversial one.
Des & Jan Howard on thu 17 nov 11
bles
*Facepalm*
Sigh!
Vince, she's all yours. I haven't time or patience for
this run around the mulberry bush.
Des
-------- Original Message --------
Subject: RE: Icebag on forehead time: magnesium and
empty bowls, wedging tables
Date: Wed, 16 Nov 2011 17:47:50 -0500
From: Notime Forspam
To:
> Firstly we're not talking about salt.
> We're talking about hydrochloric acid and chlorine
> vapors/fumes.
> However let's consider salt. If you get a load of
> salt directly into your lungs - it will do damage.
> Normal saline is only .9% saline - it's called
> "normal" because that's the normal saline content of
> human blood. Anything much stronger than that
> internally is very definitely Not A Good Thing.
> Soj
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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