David Martin Hershey on sun 28 mar 04
Hi Joanie and All,
I thought a few of you might be interested in how I've dealt with my
silica/dust/fume problems. If you don't like long posts, hit delete now!
Over the years I've had to handle a lot of hazardous materials, beginning
with my first job at 16 doing grunt work in a major chemical plant. I guess
I was lucky to learn about the value of safe work practices early on - from
seeing the damage these toxic materials did to the old timers before OSHA
came about.
A couple of years ago my work brought me to making my sculptures out of
clay. When I built my ceramic studio, I first read about the hazards, and
built it with health & safety in mind right from the start.
Here's where I need to give a big Aloha to the ClayArt archives!
Ron, you and all the others who have taken the time to discuss these issues
are saving people from tremendous needless suffering.(at least those who
care to listen) And believe me, there are few things in life more horrible
than to have to helplessly watch someone die of respiratory failure or
chemical poisoning...
Anyhow, most of my current pieces are cast, and this involves cleaning a lot
of greenware. We use knife & sponge pre cleaning, then soft firing with
full wet final cleaning, but there still is the inevitable dust. To deal
with it, I built what I call our cleaning table. It is kind of like the dust
hood that Earl was talking about last month, but I would call it more of a
dust fence.
Visualize a table about 4ft long by 2ft deep, with an 18" high fence of
furnace filters surrounding the table on 3 sides, with a "lid" covering the
back 1/3 of the top opening. These filters are backed by a 6" deep box
plenum, that feeds to a fan that I took out of an old downdraft kitchen
ventilator. (my inspiration)The fan has a squirrel cage blower, that feeds
to 5"round rigid duct, that is piped to the outside.
I was just wildly guessing when I built this thing, but it is remarkably
effective. You can hold a cigar (the horror ;-) over a foot away from the
filter, and it will draw and capture all the smoke sideways.
In fact it is so effective, that the LARGE quantity of micro fine dust that
was getting past the filters burned up the bearings on the old fan motor in
about 18 months. I have since added a finer secondary filter in front of the
fan- we'll see how long the new motor lasts. This table is also especially
good for measuring glaze materials.
My next modification will be to add filtration to the "lid". I have noticed
on occasion that when I accidentally dump some glaze chemicals, some of the
resulting dust cloud makes it past the lid and the capture power of the
fence. I am also going to buy permanent cleanable electro static filters.
Expensive, but will pay off in added efficiency and dollars eventually.
The motors on this type of fan are very small- .066 HP, and I doubt that it
costs more than a dollar or two US to run it all day. If any of you are
interested, I can email you pictures.
For secondary dust capture in the studio, I installed a Delta industrial
1200 cfm room air cleaner near the ceiling. It can filter the studios air
completely more than 10 times per hour, and is rated to capture up to 99% of
1 micron particles.
As most of you know, it is the sub 5 micron particles that are the most
dangerous ones. You can't see them, and they are so light that they never
settle to the ground. They just continue to circulate about until you
breathe them in, where they become lodged deep in the lungs. This is what
causes silicosis and other related diseases.
The only problem with the Delta is that it is somewhat noisy.(maybe 65 db)
My solution is to crank up the stereo. I try to run the Delta at least a
half hour per day to capture those rogue particles, and I always run it when
I mix plaster, etc... It costs about US $270 at Amazon.
For kiln fumes, I installed an enviro-vent on my Skutt electric kiln. I
decided to use rigid 4" ducting for longevity, and wrapped all joints with
aluminum furnace vent tape- not duct tape. I could never have a kiln indoors
without a vent, and with it I get the benefit of better firings.
The only major disadvantage of the enviro-vent is that you can't turn it off
until
the kiln has cooled below 500 or so, or it will be damaged by the heat. This
is not really a big problem for me- I just use my digital controller to
control the rate of firing down, and below 1,500f the vent helps to cool the
kiln faster.
For glazing, all of my pieces are sprayed. I bought one of those great
polyethylene spray booths from Laguna, and it is well worth the money. It
has a 12" belt driven tube-axial fan, that can capture all mist and dust
anywhere near the booth opening. The knockdown filters are very effective.
After spraying many gallons of glaze, there is only a small amount of powder
behind the filters.
I put a fine white secondary furnace filter just in front of the duct
outlet, and it was barely light gray after spraying 5 gallons of black
glaze. The booth is very easily cleaned in 5 minutes with a sponge and water
after working- no black glaze crud to get in the white glaze.
The only problem with the spraybooth is that it is REALLY noisy.(maybe 100
db) The noise is not so much from the motor, but from the fan blades and the
actual wind noise.(this thing really sucks) My solution to this problem is
to use foam earplugs rated at 33 db reduction when I spray, and to really
really crank up the stereo...
Of course I still use a good respirator with pre-filters when spraying,
mixing glazes, etc. Respirators have really come a long way in recent years.
I got a new one from 3M, and it is far superior to the old black rubber
"Mine Safety" model I had been using for 20 odd years. It is made of soft
silicone like a skin divers mask, doesn't leave much of a mark on your face
after wearing it for hours, and it doesn't stink like inner tubes!
In fact it is so good, that when I take it off, I am always momentarily
overwhelmed with the normal smells of the studio after breathing sterile air
for an hour or more.
Here's the blurb & a web source:
http://www.envirosafetyproducts.com/html/Subcategories/7500series.htm
"NEW Half Facepiece Respirators - 7500 Series - Ultimate Reusable
Years of research and development went into the creation of the new 7500
Series half facepiece respirator. Experience a new level of comfort as a
result of state-of-the-art features built into the 7500. Features such as
the new soft seal design provide a softer feel and reduces pressure points
on the face. The Cool FlowT Exhalation Valve will help make breathing easier
and help reduce heat and moisture buildup in the facepiece. Extensive field
testing results have shown that customers prefer the 7500 to their current
respirator."
One last thing on breathing protection. If you just feel too claustrophobic
to wear a regular respirator, you CAN get protection from up to 95 percent
of harmful silica and spray particles with certain paper masks. In the US
they must be NIOSH rated for dust/mist hazard (on the mask stamped N95), and
usually include two straps, a rubber seal, and an exhalation valve. They
must be worn properly, and cost about US $3 each in a box of 10.
Finally, I'm also a big fan of protecting my hands. I never put my bare
hands in glaze, slip, plaster, or chemicals of any kind. I wear the recently
discussed nitrile gloves, in the 5 mil thickness. The great thing about
nitrile is that when they fail, they fail completely- literally falling off
your hand. You never get a pinhole leak in one of the finger tips, that goes
undiscovered until your finger has turned into a prune.
One pair of gloves can last a week or more, and I NEVER have cracked or
badly damaged skin on my hands... . I don't throw on the wheel, but I'm sure
that if you got the right size, you could use them for that. (they come in 5
sizes)
I hope some of this is helpful.
Best, DMH
From Beautiful Hermosa Beach CA.USA
Where the baby dolphins have been feeling frisky all month!
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