Respirator -dust masks

Must a full face respirator be used for mixing relatively small
amounts of investment for casting, or are there any specific dust
masks that members can recommend that offer sufficient
protection? MR

There is a new rating system for dust masks that requires that
they have a code stamped on the mask to indicate the efficiency
of the mask. I called 3M about a month ago and was told that the
dust masks marked N95 or N100 are good enough for silica dust
from investment. These are the top of the line dust masks but it
is cheaper and more comfortable than a respirator.


Hi James,

just make sure those dust masks rated for silica fit snugly
around the chin and nose area. It’s common for dust masks not
to fit properly on everyone since everyone has a different
shape/size face. There are often gaps around the nose and chin.
Any gaps and you’re still breathing silica.

Respirators are a pain I know, but they usually fit well.
Technically they should be tested for fit as well.

Best Regards,

Elaine Corwin
Tel: 1-800-544-2043 ext. 287
Fax: 203-335-0300

Hi Elaine,

Coming from a background where a proper respirator fit

literally meant staying alive. I understand the necessity for a
good fit. ( A very cranky old nuke submarine that had a series
of fires during the time I was on board, no fun :frowning: ) Most
people do not know how to test fit a respirator or dust mask and
in the case of the respirator they almost never change the
cartridges which are only good for about 8 hours of use! As an
industry we really need more understanding of these devices and
their proper use.


James Binnion Metal Arts
4701 San Leandro St #18
Oakland, CA 94601