Eric Suchman on sat 13 dec 03
Bob,
Where are you located? Perhaps some one has a use for it.
Eric in Oceanside
> From: "Bob U."
> Reply-To: Clayart
> Date: Sat, 13 Dec 2003 22:11:08 -0500
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Contaminated Kiln
>=20
> Hello All, I have a question regarding a kiln I have obtained for free fr=
om
> a relative (he purchased a new kiln). After obtaining the kiln, I procee=
ded
> to set it up and prepared to fire it. But before I actually used it, the
> relative I obtained the kiln from mentioned that he used leaded glazes in
> the kiln on his sculptures. I=92m not really sure why, but he did. I
> researched kiln lead contamination in the clayart archives and immediatel=
y
> became concerned based on what I learned. I went to the store a purchase=
d
> two different brand lead test kits and tested the kiln. Both tests were
> positive for lead on the firebrick on the walls and lid in multiple
> locations. Once I found out the kiln was contaminated, I moved the kiln =
out
> of my house into the garage where it now sits.
>=20
> The question is =96 what do I do with this kiln? I assume the kiln really =
has
> no value at this point and should be trashed. How do I get rid of a
> contaminated kiln? I really don=92t want anything to do with this kiln
> anymore. Any suggestions? In case it matters, the kiln is an old Knight
> model 82 with a max temp of 2300 F and has a Dawson Kiln Sitter and timer=
,
> about 3 cu-ft or so.
>=20
> Thanks,
>=20
> Bob U.
>=20
> _________________________________________________________________________=
_____
> Send postings to clayart@lsv.ceramics.org
>=20
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>=20
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Earl Brunner on sat 13 dec 03
If you can fire it in a well ventilated area, take it to max.
temperature with all of the peep holes open and see if you can blow some
air through it. Some very experienced potters that I know, (and this is
just theory on their part as far as I know) have discussed this and feel
that since lead vaporizes at that high end, that one should be able to
"clean" a contaminated kiln in this manner. But I don't know anyone for
sure that has done it or proved it one way or another. Just an idea.
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Bob U.
Sent: Saturday, December 13, 2003 7:11 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Contaminated Kiln
Hello All, I have a question regarding a kiln I have obtained for free
from
a relative (he purchased a new kiln). After obtaining the kiln, I
proceeded
to set it up and prepared to fire it. But before I actually used it,
the
relative I obtained the kiln from mentioned that he used leaded glazes
in
the kiln on his sculptures. I'm not really sure why, but he did. I
researched kiln lead contamination in the clayart archives and
immediately
became concerned based on what I learned. I went to the store a
purchased
two different brand lead test kits and tested the kiln. Both tests were
positive for lead on the firebrick on the walls and lid in multiple
locations. Once I found out the kiln was contaminated, I moved the kiln
out
of my house into the garage where it now sits.
The question is - what do I do with this kiln? I assume the kiln really
has
no value at this point and should be trashed. How do I get rid of a
contaminated kiln? I really don't want anything to do with this kiln
anymore. Any suggestions? In case it matters, the kiln is an old
Knight
model 82 with a max temp of 2300 F and has a Dawson Kiln Sitter and
timer,
about 3 cu-ft or so.
Thanks,
Bob U.
________________________________________________________________________
______
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Bob U. on sat 13 dec 03
Hello All, I have a question regarding a kiln I have obtained for free from
a relative (he purchased a new kiln). After obtaining the kiln, I proceeded=
to set it up and prepared to fire it. But before I actually used it, the
relative I obtained the kiln from mentioned that he used leaded glazes in
the kiln on his sculptures. I=92m not really sure why, but he did. I
researched kiln lead contamination in the clayart archives and immediately
became concerned based on what I learned. I went to the store a purchased
two different brand lead test kits and tested the kiln. Both tests were
positive for lead on the firebrick on the walls and lid in multiple
locations. Once I found out the kiln was contaminated, I moved the kiln out=
of my house into the garage where it now sits.
The question is =96 what do I do with this kiln? I assume the kiln really h=
as
no value at this point and should be trashed. How do I get rid of a
contaminated kiln? I really don=92t want anything to do with this kiln
anymore. Any suggestions? In case it matters, the kiln is an old Knight
model 82 with a max temp of 2300 F and has a Dawson Kiln Sitter and timer,
about 3 cu-ft or so.
Thanks,
Bob U.
Jim Murphy on sun 14 dec 03
Hi Bob,
Say, I don't know if this really works or not, but, I recall reading in some
pottery book about placing Nepheline Syenite in a bisqued bowl in the kiln
and firing to 1000 C. I believe the Neph Sy was supposed to somehow absorb
Lead fumes out of the firebrick.
Again, just working from memory - never tried it. Maybe somebody else knows
something about this.
Best wishes,
Jim Murphy
John Hesselberth on sun 14 dec 03
On Saturday, December 13, 2003, at 10:11 PM, Bob U. wrote:
> The question is =96 what do I do with this kiln? I assume the kiln=20
> really has
> no value at this point and should be trashed. How do I get rid of a
> contaminated kiln? I really don=92t want anything to do with this =
kiln
> anymore. Any suggestions? In case it matters, the kiln is an old=20
> Knight
> model 82 with a max temp of 2300 F and has a Dawson Kiln Sitter and=20
> timer,
> about 3 cu-ft or so.
Hi Bob,
Try this if you want to salvage the kiln. First, let me say the actual=20=
amount of lead in the kiln is extremely small--almost certainly well=20
less than you would put into the environment by losing a small lead=20
sinker while fishing. That said, you don't want it deposited onto your=20=
pots. Fire the empty kiln as hot as it will go with the peeps open and=20=
the lid cracked open in a very well ventilated area. Then cool it and=20
retest for lead. Repeat a couple more times if necessary. This=20
technique has been suggested several times on Clayart, but no one has=20
(to my knowledge) ever reported back on whether or not it worked. Then=20=
clear your environmental conscience by committing to switch to steel=20
sinkers for your future fishing expeditions.
Regards,
John
http://www.frogpondpottery.com
http://www.masteringglazes.com
Frank Bales on sun 14 dec 03
I'm a neophyte, but if it's the brick that contaminated, can't the brick in
the kiln be replaced? --FrankB
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Jim Murphy
Say, I don't know if this really works or not, but, I recall reading in some
pottery book about placing Nepheline Syenite in a bisqued bowl in the kiln
and firing to 1000 C. I believe the Neph Sy was supposed to somehow absorb
Lead fumes out of the firebrick.
Rick on mon 15 dec 03
I don't have anything to offer, but I'm following this with interest
and hoping you are able to clear up the problem because throwing out a
kiln sounds like too great a loss and clearing out the lead
successfully would surely help some future potter(s).
Rick
On Dec 15, 2003, at 12:03 PM, Frank Bales wrote:
> I'm a neophyte, but if it's the brick that contaminated, can't the
> brick in
> the kiln be replaced? --FrankB
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Jim Murphy
>
> Say, I don't know if this really works or not, but, I recall reading
> in some
> pottery book about placing Nepheline Syenite in a bisqued bowl in the
> kiln
> and firing to 1000 C. I believe the Neph Sy was supposed to somehow
> absorb
> Lead fumes out of the firebrick.
>
> _______________________________________________________________________
> _______
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Snail Scott on mon 15 dec 03
At 10:11 PM 12/13/03 -0500, you wrote:
>Both tests were
>positive for lead on the firebrick...
>...I assume the kiln really has
>no value at this point and should be trashed...
Don't do that. Fire it to its max for a few nice
long firings, then re-test before deciding its
fate. Lead can be burned out. (And if you do
decide to trash it anyway, it'll be safer to
dispose of.)
-Snail
Zoe Johnson on mon 15 dec 03
Before you get to panicky about the kiln, check your local soil, the walls
of house and garage. The level may be much higher because of the lead that
was in gasoline for years and in paint, too. The amount of lead in the
everyday environment is astonishing. An even more important test than
testing the walls of the kiln after some long hot firings would be to put a
pot inside and test it after firing.
--On Monday, December 15, 2003 8:59 AM -0800 Snail Scott
wrote:
> At 10:11 PM 12/13/03 -0500, you wrote:
>> Both tests were
>> positive for lead on the firebrick...
>> ...I assume the kiln really has
>> no value at this point and should be trashed...
Paul Lewing on mon 15 dec 03
on 12/13/03 7:11 PM, Bob U. at ubobu@YAHOO.COM wrote:
> I assume the kiln really h=
> as
> no value at this point and should be trashed.
Bob, this is really overreacting, as is your moving the kiln out of your
house. I think John Hesselberth's advice about firing it up to cone 6 or so
several times and retesting is a good idea. We'd all be interested to know
the results of those tests.
But remember, this is lead, it's not cyanide. The resulting fumes are not
Serin or mustard gas. Yes, it's carcinogenic, but only with prolonged
exposure to significant amounts. There is lead in diesel fuel, so you'd
probably get more lead fumes by driving behind a bus than you'll ever get
from this kiln, and you do that every day without a second thought.
We need to think a little more carefully about risk assessment. Think for a
minute about how much lead might be deposited on a pot fired in this kiln.
Think about the glazes that were fired in this kiln. Not all of that glaze
was lead oxide. Very little of that lead vaporized, or the glazes wouldn't
have worked. Very little of THAT lead got deposited on the kiln walls. And
only a proportion of THAT lead revaporizes in any firing. Of THAT lead, only
a tiny portion deposits on the surface of any pot fired with it, and
probably even less on the inside surfaces. It's not zero, but it's very,
very tiny.
Please try this test and tell us all the results. On your first firing to
clear the lead out, put a pot you don't care about in and test it for lead
after the firing. We've been hearing for years that this can contaminate
pots fired in a kiln that has had lead glazes fired in it, but so far I have
never actually heard of anybody testing that theory. You can make a real
contribution here. Test down inside the pot where the food would go, not on
the outside. Actually, test both places.
I realize that we should all be taking all the precautions we can to protect
ourselves and our customers from harmful substances, but NONE of us can have
zero tolerance for hazardous substances in our studios and still work with
clay and glazes. We all have to draw a line somewhere.
If nothing else, give the kiln to someone who makes stuff that doesn't
contact food.
Paul Lewing, Seattle
C. A. Sanger on tue 16 dec 03
After the kiln is heated several times to gas out the lead, would
applying ITC to its interior help seal it? C. A. Sanger
ShardRock Clay Studio <:)}}}><
Herington, Kansas
Bob U. on fri 9 jan 04
Hello, I thought I would post an update on the subject with information I
received from a couple of experts on the subject. See the messages below.
From: Tri-state Kiln Service, Inc.
When you fire ceramic clays and glazes, minute amounts of some gasses,
vapors and corrosives are emitted into the kiln such as water from the
clay, carbon monoxide and corrosive acids. A kiln is designed to allow the
moistures containing some of these to leach through the bricks of the kiln
to the outside of the kiln. The corrosives will attack the metals of the
kiln from the inside to the outside and will eventually rust through the
metal jacket. This process could take years. The manufacturers have made
the jackets of the kilns out of stainless steel because it will last longer
than regular steel or sheet metal. The gases or smells were just allowed
to escape into the room where normal air circulation would eventually
dissipate them.
Restaurant type hood exhaust fans were used to vent the kiln to the outside
of the building, but the fumes and vapors had to get into the room for the
hood exhausts to remove them from the room. If the fumes containing the
moistures and vapors didn=92t get near the hood exhaust, then they weren=92t=
taken out of the room. At best a hood exhaust is about 60%-65% effective
in getting these smells and vapors out of a room.
Today=92s formulas of clays and lead free glazes emit a lot less lead than
the old ones. The Orton Downdraft Kiln Vent System is a system that draws
a small amount of air through the kiln, picking up the gasses, vapors and
corrosives and blowing them to the outside before they even have a chance
to enter the room. This kiln vent is about 90% to 95% effective.
With all of this in mind, the lead in the bricks of an older kiln is a
normal thing. I don=92t know if you will ever be able to get it out of the
brick. Maybe through use more gases, vapors and corrosives that are not as
abusive will enter the bricks and eventually push the lead out of them. I
recommend you calling the Orton Firing Institute and talking to them about
this issue (see response below). These people make a business of studying
what happens in a kiln and to a kiln during the firing processes. If they
can=92t answer the question then no one can. You can reach them at area cod=
e
614-895-2663. They also have a WEB site at www.ortonceramic.com.
If you can=92t get an answer to your question, E-mail me again or call me at=
847-623-2957 and I will try other sources., but I think I have directed you
to the best one first.
Good luck.
Mike Rovner
From: Orton Ceramic Fdn.
Dear Bob,
I do not know of a safe and sure-fire way to remove lead from the lining of
a kiln. Once it is in the pours of the brick it would be very difficult to
extract. It will vaporize at high temperatures so using a kiln vent will
exhaust the vapors, but not all of them. There will always be some residue
that deposits, on cooling, back onto the kiln walls and even your ware.
Sorry, but the only way to insure that your kiln does not have a high
lead level is to not introduce leaded glazes in it in the first place.
Best Regards,
Tom McInnerney
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