MiamiCuse wrote:

I posted an inquiry a few weeks ago about cutting old plastered wall that is
has af gypsum lath as a double layer wall board.

I need to cut small holes on these existing walls for electrical outlets,
intercom units, and also old demolished walls that have unclean tearouts at
corners that have embedded wire meshes. Initially I tried to use a
recipricating saw, no luck, then tried a rotaty tool and that worked fine
for like 5 minutes, then today I tried an angle grinder and it worked.

I knew it would be dusty, so I prepared and worn an extra layer of clothing,
I put on a cap, a twin catridge respiratory mask, a eye protecting mask and
went to work. It was DUSTY. When I cut the corner joints at the ceiling
there were so much dust flying it's like snowing right into my face. I
forged ahead and kept going. Soon I can't see the chalk lines I drew
because it was so dusty. I opened the doors and the dust started to float
outdoors and it does not settle, it seems to float up.

I took my mask off and it has dust inside the mask, which was unexpected
since I was wearing it very tight. Next I have this gritty taste in my
mouth, did the dust get inside the respirator? I looked at myself and I am
like snowman. I had some of this dust in my hand and it didn't feel like
dust it's like silt and it's all over me. I am starting to worry...does
plaster (built in 1972) have asbestos? It seems to have gotten inside every
of my pore, I mean, I was wearing long pants outside and shorts inside, and
I had my cell phone inside my short back pocket. When I cleaned up and took
out my phone, I flipped it open and it opened half way, dust got inside the
hinge and clogged it! How does it get past two layers of clothing?

I am only half done, after doing this for about six hours, but I am
hesitating to go forward without knowing more about this dusty silt and if
it could be a health hazard. Is there a mask that can protect against this?

Thanks,

MC

I very much doubt that there is asbestos and even if there was,
long term exposure is the problem with that. Of course, none is
better, but I wouldn't worry about it unless you plan to do this
on a regular basis for the next few years.

The mortar does have silica, which is a known hazard, but this is
also a long term exposure problem rather than just a one time
danger. If you don't plan on doing this for an extended period
of time (years), then you don't have anything to worry about
except for (excuse my vulgarity here) strangely white boogers.

You have discovered the joys of cutting concrete! Be thankful.
You won't have to stay up nights wondering anymore! Horrible,
isn't it? You will be finding this in cracks and crevices for a
long time. It is a very fine dust almost like talc.

A common particle mask is ok for this type of dust. A respirator
is fine, too, but probably overkill. If you have to do any more,
then take your shop vac and hold the nozzle so that it sucks up
the dust as you cut. Makes an amazing amount of difference and
you will not have so many problems with dust. You may have to
clean the filter on your shop vac more than usual.

Be warned that this type of dust is the absolute WORST for
electric tools. It is abrasive and gets into the windings and
gears and bushings, etc. We always have a lesser quality grinder
or saw to do this work with and we clean it with a high pressure
air hose after use. (Start the grinder and then blow out every
crevice that you can find until dust stops blowing out.)

Good luck and don't worry.

--
Robert Allison
Rimshot, Inc.
Georgetown, TX