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Hi John,

>Is there anyone with experience/opinion on using
>masks while working with solvents.  I have a mask
>for use with organic gases (3M 7300 with 7155
>filters).  Is this effective?
Speaking from 30+ years of exposure with both MC & Acetone in the manuf
of Lexan plastic (GE employee), I would still recommend using as much
ventilation and fresh air as you can manage.  The use of masks would just
be insurance.  Our rule of thumb at GE was (after being in fresh air long
enough to clear any past exposure) if you could smell the stuff through
the mask, it was surely not doing you much good.
We never used masks for routine work and used the Scott air pack type of
pressurized air tank for 'escape' purposes.

In building the Lancair (as I think I mentioned in a previous posting) I
built a three by five foot lab-type hood with a medium sized squirrel
cage fan drawing air outside under which I mixed epoxy and for acetone
clean up of the application tools etc.
When 'cleaning' a large area on the airframe in preparation, I opened the
doors and used a box fan to blow the vapor away from the work area.  Both
MC and Acetone 'boil' rather quickly at reasonable temperatures so they
will leave the area in a short time.

I hope this helps.  Earl