My question is, does anyone on this list have some actual
experience using any of these things in dusty, hot lapidary
Yes, sort of. I was a professional potter for 20-some years before
becoming a jewelry-maker. I always wore a mask when mixing powdered
minerals such as clays and glazes-- micro-fine particles of quartz
and silica, copper, cobalt, manganese, etc.
I always used a 3M particle mask with two cartridges, the kind that
makes you look, sound and feel like Darth Vadar. It takes getting
used to, but you will not actually suffocate. It is just a little
more work to breathe. I took care of my mother while she died from
emphysema, actually unable to breathe (from smoking, not silicosis),
so I'm more than willing to endure the temporary difficulty.
So hang in there, keep using a good mask, just get used to it, and
keep it snug. How often you need to change it depends on how bad the
conditions are when you use it, but the manufacturer's instructions
should help you out on that.
One thing that potters tend to do, if they don't really think about
it, is leave the mask just lying around in the studio when not in
use. Clearly, you don't want dust settling on the back of the
mask, where you will immediately suck it into your lungs when you
put it on. So keep it in a bag, box, or other dust-tight container
when you don't need it.