Craig Clark on mon 19 sep 05
Nathan, first, there is a reasonably high probability that the
blanket is asbestos if was obtained many years ago. Ask how old the
blanket is and you will get a pretty good idea. Fiber blanket (ceramic
fiber insulation in the form of a blanket) wasn't used that widely until
the early seventies as far as I know. Asbestos was fazed out very
slowly. It wasn't until the likes of our very own home grown Walter
Umphries who went the distance with the asbestos manufacturers and won
the first of several multi-million dollar law suits that asbestos
manufacture and use began to decline. If the blankets are asbestos I
don't care how free they are......toss them or entomb them. Don't breath
the fibers!
The "rock wool" that you mentioned is most likely a trivial name for
ceramic fiber blanket insulating blanket.It is also known as Inswool and
Kaowool. It comes in a variety of sizes, shapes and flavors. There is
stuff on the market now that is good for a hot face with a continuous
duty cycle of 2800 F and higher.
If you are going to use a blanket of any type to insulate a kiln in
which you will fire pottery then ceramic fiber blanket is what I
strongly recommend. Even if the boiler blankets are free, you really
aren't saving much money anyway. Ceramic fiber insulating blanket has
gotten down right cheap, at least if you compare it to what it used to
cost.Remember, there are a whole bunch of things that figure into the
cost beyond the original price of the material.
Hope this helps
Just say no to asbestos
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
John Baymore on mon 19 sep 05
Hi. There is not enough real info there to be very certain. So I'm
really guessing here.......
If it is really "old"... and associated with boilers...... the "canvas" is
possibly asbestos cloth and the "rockwool-ish" looking stuff is probably
asbestos fibers.
If you can't verify the material... you really should assume that it IS
asbestos..... and handle it appropriately. Wheich basically
means ......... don't .
Another possibility is that the "canvas" is actually Kevlar cloth, and
the "rockwool" is actually RCF (refractory ceramic fiber). RCF .........
particularly if it is used and has been heated repeatedly to high
temperatures........ can contain a LOT of respirable microcrystalline
qyartz ... in the cristobalite form. Nasty stuff to breathe. Because
they SOUND like they probably werre used at low temps... that might not be
an issue. But RCF is very "suspect" material anyway...... as far as it's
possible carcogentetic properties. Be careful with it even if it is not
asbestos.
And do you have any idea what it might have been contaminated with in its
prior life?
Hope this helps.
best,
..............john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
JBaymore@compuserve.com
http://www.JohnBaymore.com
"Please use compuserve address for any direct communications."
nsmheralds@netzero.net on mon 19 sep 05
Greetings unto the list. My father-in-law has in his possession a number of "boiler blankets." He obtained them "many years ago for next to nothing" and has offered them to me for use in the oil drum kiln I'm building. It's about 1.25 inches thick and is covered with "fireproof canvas" which he says can be easily removed. Since free is a very good price, how could I refuse? There are, however, a couple of questions and concerns that need addressing before I attempt to use them.
I need to determine its composition. My father-in-law says he's going to look at the stuff under a microscope to see if he can determine whether it's asbestos or ceramic. Aside from the obvious carcinogenic issues associated with asbestos, what other aspects of the material might make it unsuitable for use as the primary insulation in my kiln? I've also heard of something called rock-wool. What is it? Is it likely to be the material in question? If so, should I attempt to use it as my insulation?
Does anyone know anything about the aforementiond canvas? Or is it even canvas at all and not something else woven to a similar texture? I hypothesize that it was standard equipment on boiler insulation. Certainly, "fireproof" is a relative term and this stuff would, if I left it on, be subjected to temperatures up to cone 12. Would the worst that could happen be that it would just catch fire and be summarily ejected through the exit flue? Or would I also run the risk of having bits of it sticking to my pots? I'm not too worried about this last bit, since I'm using rejected bisqueware as test pots in my maiden firing. It would, however, be useful to know what kind of treatment the canvas is likely to have had. I was originally planning to treat the interior of the kiln with ITC 100. If the canvas has already been treated with a similar refractory material to make it fireproof, trying to add ITC 100 might be counterproductive depending on the nature of the aforementioned mate
rial.
Anything that anyone can tell me about this stuff will be very useful. Thanks.
Nathan Miller
Newberg, OR
Steve Slatin on mon 19 sep 05
Nathan --
Disclaimer first- I know NOTHING about boiler
blankets, and can't even speculate on what's involved
in the 'canvas' layer.
Rock wool, though, I know a very little about -- it's
amorphous silica and a binder, often an oil-based
binder, to provide dust suppression. (It's called
rock wool because it's made from rocks.) AFAIK, all
tests have shown it not to be carcinogenic, but it is
an irritant -- eyes, throat, lungs, and the like --
though it's fairly inert in normal use.
Normal use, though, doesn't include stripping off
protective layers and so on. I removed some from an
attic once, and coughed for DAYS. (And I did use a
mask while removing it.)
-- Steve Slatin
--- "nsmheralds@netzero.net"
wrote:
Steve Slatin --
Drove downtown in the rain
9:30 on a Tuesday night
Just to check out the
Late night record shop
__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com
Edouard Bastarache Inc. on tue 20 sep 05
Hello Craig,
if you want to read my text "in extenso", go to :
http://perso.wanadoo.fr/smart2000/Fibres_artificielles.htm#english
Man-made vitreous fibers (MMVF)
Introduction :
Man-made vitreous fibers (MMVF) or synthetic vitreous fibers (SVFs) are a
class of
insulating materials used widely in residential and industrial settings;
they are made
primarely from glass, rock, slag or clay. The three general categories are
fiberglass,
mineral wool , and refractory ceramic fibers.
In some situations, SVF materials can release fine, airborne dust particles,
some of
which are small enough to be respirable. Thus, workers may be exposed to SVF
fibers by dermal contact and/or by inhalation.
Fibrous particles having long, thin geometry present a special problem to
the resiratory
tract; because fibers are thin, they can penetrate into the deep lung and,
because they
are long, mobile lung cells may have difficulty in removing them.
(...)
B-Mineral Wool :
1-Rock Wool,
2-Slag Wool.
(...)
B-Mineral Wool :
Mineral wools include rock or stone wool and slag wool. After formation, the
materials
are sprayed with lubricating oils and binders to reduce dustiness (mineral
wools generally
contain a very high ratio of nonfibrous particles, or shot) and fiber
breakage.
Mineral wool applications are very similar to those of glass wool-thermal
insulation,
including fire protection, and acoustic insulation. Much of the mineral wool
produced
is used for blown-in insulation in attics and side walls. Another popular
use of mineral
wool is in the manufacture of decorative and acoustic ceiling tiles for
commercial
building.
(...)
Health effects summary
The ban on the use of asbestos resulted in a larger and larger use of
substitution
materials in many industrial processes and in particular the use of man-made
vitreous
fibers (MMVF).
In rodents, inhalational studies show that glass insulation wools and slag
wool produced
no permanent injury, even after 2 years of exposure to high concentrations
(at least 300-fold the concentrations to which human SVF workers typically
are exposed).
In more recent rodent inhalational studies, two durable SVFcompositions were
associated with
permanent lung injury : rock wool (MMVF21) induced fibrosis late in the
study, and RCF
induced fibrosis and tumorigenesis. Other durable fibers are pathogenic to
animals : glass
microfiber E may also induce fibrosis and tumorigenesis in rats, fiber glass
475 induces
fibrosis and possibly mesothelioma in hamsters but not in rats.
In man, the main part of known health effects comes from data collected
among workers
of industries producing these fibers, where the levels of exposure were low,
much lower
than those encountered in many professional situations by the finished
product users.
Even if the relationship to the exposure to rockwool fibers/slag wool fibers
is not clearly
established, the observation of an excess of bronchopulmonary cancers among
workmen
producing these fibres must prompt us to be vigilant and to control levels
of exposure to
these fibers in the work environment. The SMRs for bronchopulmonary cancer
are lower among workmen of glass wool production than among workmen of
rockwool/slag wool production.
Taking into account data observed in experiments (excess of tumours) and
preliminary information obtained from man (suspicion of an excess of benign
pleural pathologies, and of respiratory functional impairment of the
obstructive type),
an attitude even more careful is essential with respect to refractory
ceramic fibres.
These fibres were classified in category 2 (similar substances to
cancerogenic
substances for man) by the European Communities.
Nothing currently makes it possible to affirm that a risk of nonmalignant
respiratory
pathology exists for man with rock, glass, and slag fibers. Nevertheless,
experimental
data showed a real pathogenic effect for levels of exposure close to those
producing the
same effects with asbestos. Certain fibers, as some made from glass, appear
sufficiently
soluble to have no irreversible effects.Others like ceramic fibers are more
suspicious.
The absence of sufficient experience must prompt us to pursue epidemiologic
and
experimental studies, and to introduce an effective prevention policy.
Later,
"Ils sont fous ces quebecois"
"They are insane these quebekers"
"Están locos estos quebequeses"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
www.sorel-tracy.qc.ca/~edouardb/Welcome.html
http://www.flickr.com/photos/potier/
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
John Baymore on tue 20 sep 05
I can't beleive that I let that terrible mis-spelling slip through on my
posting about the boiler blankets.
"Carcinogenic" ... not whatever the heck my terrible typing came up with.
And Edouard... thanks for adding the details on RCF... this has been a
subject that has concerned me for a long, long time. I cringe when I see
or hear how some potters just toss the stuff around casually.
best,
................john
John Baymore
River Bend Pottery
22 Riverbend Way
Wilton, NH 03086 USA
JBaymore@compuserve.com
http://www.JohnBaymore.com
"Please use compuserve address for any direct communications."
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