Thank you Bob - I just learned a valuable lesson - this will go in my save
file and I will make a trip to the hardware store tomorrow. Donna

"Bob Masta" wrote in message
...
On Thu, 17 Jul 2008 19:21:57 -0400, "D Kat"
wrote:

snip
When mixing up glazes or
clay it should be done with a mask and you and your clothes should be
washed
afterwards. The fine dust of silica can stay in the air for days - spray
the area with a mister after playing with materials.

Not trying to be picky here, just want to make clear to any clay
newbies that "mask" is *not* one of those little disposable "dust
masks" they sell in the paint aisle for a buck or two. It should be
what they typically call a "respirator" that covers the bottom half of
your face with an air-tight seal. These have replaceable filter
cartridges rated for various substances. If you buy the unit at your
local hardware store, it will probably come with "Organic vapor/P95"
for paint and pesticides. This is really a 2-stage unit: The vapor
cartridge is the bulky part closest to your face, which is typically
removable via a twist-lock. You don't care too much about this part
for pottery work. Just leave it as-is.

The "P95" is a fuzzy white particulate filter pad that goes over the
cartridge, usually with some sort of simple snap arrangement.
P95 means it is rated to remove 95% of the particulates bigger than
0.3 micron ("fume sized" particles). While that is orders of
magnitude better than a disposable dust mask (those *always* leak air
around the edges), it is recommended that you get a P100 replacement
filter. These remove 99.97% and are also called "HEPA" for High
Efficiency Particulate Air filters. As far as I know they are always
pink, not white. (There are also apparently thinner/chaper N100 and
R100 versions that need replacing more often, but I've never seen
them.) Replacement P100 pads are around $5.00 per pair from on-line
suppliers.

The main thing with a respirator is that it *must* have an air-tight
seal around your face, so that all the air you breathe in comes
through the filters. That requires a soft rubber construction with a
very flexible lip or edge. When you buy a respirator, the
instructions explain how to test for a good seal. Some designs may
work better than others with your particular face shape, especially
for those with beards. If you don't have a good seal, you don't have
a respirator... take it back and try again! (Maybe you could try on a
friend's ahead of time, to see if that model is right for you...
someone who doesn't mind sharing "cooties" with you!)

Best regards,


Bob Masta

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