Vince Pitelka on mon 13 may 96
Pete's post is well taken, and I second his caution. For the past twenty years
we have been understandably infatuated with the wonders of ceramic fiber - one
of those miraculous products of the space-race and/or defense industry that has
found it's way into other usage. But there has not been nearly enough concern
about the potential risks of fiber. As I see it, when fiber is used as a
lining inside a proper rigid frame or an existing kiln, and when it is sprayed
with the correct rigidizer, and great care is taken to avoid abrading the
surface, then the danger is minimal. Am I correct in this assumption?
I have seen several particular areas of danger. I agree with Pete that one of
the best raku kilns is a recycled electric converted to gas, but if you do
choose a fiber-lined raku kiln, be sure to use a cylinder that is completely
rigid. If the cylinder flexes in use and transportation, the fiber will break
down quickly, and spraying with a rigidizer in this situation will only
aggrivate the problem. Another area of concern is in using ordinary ceramic
fiber blanket as a gasket on kiln lids or doors. This fiber compresses every
time the lid or door is closed, and soon breaks down and releases particles
into the atmosphere. If you feel you need to use a gasket, use a proper woven
fiber gasket, available from ceramic fiber suppliers.
I have also seen people place a layer of fiber over the lid of a toploader
electric to decrease heat-loss through the lid. If you feel this would be a
benefit, install the fiber permanently with a sheet-metal shell holding and
sealing it in place. Our director, Ward Doubet, converted an old toploader
into a nice little ^10 gas updraft. He removed the stainless-steel jacket,
added a layer of fiber outside the brick, and reinstalled the jacket with a
strip of sheet metal added to cover the increased diameter. Again, the fiber
is sealed beneath the jacket, and is no danger.
In most "kaowool"-type products the fibers are small enough to remain airborn
for some time, and if inhaled into the lungs the effect is like that of silica
dust. The cilia on the inside surface of the lungs does not have the ability
to expel these fibers, and instead the body responds by forming a nodule of
scar tissue around the fiber or silica particle. Each nodule is a little less
lung capacity, and the results are cummulative and non-reversible. There is
such a thing as carrying one's concern to an excessive degree - If you go
hiking in a rocky area, and if someone is walking ahead of you, there is going
to be some silica dust in the air. It's unavoidable. The idea here is to
minimize our inhalation of potentially carcinogenic materials in the studio,
and in this regard every little measure helps.
- Vince
Vince Pitelka - wkp0067@tntech.edu
Appalachian Center for Crafts - Tennessee Technological University
Smithville, TN
| |
|
