Hi Dee, Regarding lost wax casting and breathing problems - you should
always wear a respirator when working with or around casting
investment. The silica in the investment gets in the air, and into
your lungs, never to return again. A great deal of silica is also
released into the air with the steam when a flask is quenched.
Especially over repeated exposures, this can be quite detrimental to
your health.
A few years ago I took a class at the well-respected community
college… just for some camaraderie… everyone looked at me like I
was nuts when I “geared up” to start mixing investment. Even after
setting the example and explaining why I was doing it, nobody else
followed suit. You can lead a horse to water, but you can’t make him
drink.
P.S. How’s that for a peculiar Yankee expression?!? 
Does that make
sense in translation?
All the best,
Dave
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com
http://www.CarolinaArtisans.com