In a message dated 12/2/98 11:23:46 AM Eastern Standard Time,
[log in to unmask] writes:
> I have been asked recently on the most up-to-date and best method for
removing VERY attached paint from brick. I told the owner of the home
definately NOT to sandblast, and that there were more ecologically friendly
ways to attempt to remove the paint. He said he had heard of baking soda being
used in place of sand (this still sounded pretty abrasive to me). Suggestions
from our masonry mavens?
The hazardous material in most paint removal projects is the paint, so
whatever method you use you should check the paint first for lead content
before dumping it into the environment.
Paint stippers using methyl chloride may be cancerous and should generally be
avoided. Breathing solvents is not considered good for your health despite any
alterations to your state of mind. Gel strippers will burn the hair and skin
off your tummy if you happen to get it on your shirt, trust me, been there,
done that. Rinse with water and remove contamiinated clothing immediatly.
Sand used for blasting does not become hazardous as debris, it is hazardous
during the process of blasting because breathing silicates leads to silicosis.
A condition to be avoided. Sand, as a component of many of our ocean beaches,
is not usually considered a hazardous material until it is put in a bag and
sold in a store, at which point all kinds of warnings are printed on the back
side of the bag. Though baking soda blasting is considered environmentally
friendly, it is of very little effectiveness for removing brick from paint. I
think it is effective for removal of graffiti from things like stop signs and
coke cans. We have used plastic media for removal of epoxy paint and
bituminuous cement from hard brick with no obvious damage to the brick -- but
it was a HARD brick. This stuff, relatively expensive, is used to strip paint
from aluminum bodies of aircraft. We have also used 10,000 psi hydra silica
blasting with obvious damage to the brick. This equipment is used for cutting
concrete grade beams. Our favorite blasting methodology is using walnut shells
for paint removal from cast iron. We used this on the Simon Bolivar statue in
Central Park several years ago. I forget what we used to remove the gilding
from the Prometheus Statue at Rockefeller Center, I think it may have been
crushed glass. You can also get beaded glass, though the effectiveness is
different. Corn cobs & pecan shells, as well as slag and aluminum oxide are
fun to play with. Dolomite blasting is possibly effective for paint removal,
but relatively expensive to acquire the equipment. Lazers seem to be
expensive, something like $30.00 p/sf, that is, if you can find the equipment
-- it is popular in France. I know of a guy that suggests blasting with bee
renderings. Might as well use butter.
My recommendation for controlled removal of paint from masonry is to use a
solvent based poultice. Removal of the debris can be controlled. And then
application of a non-methyl chloride gel stripper followed by a 500 psi max
water wash. Hot water works best.
If you are removing lead paint then you should be concerned about exposing
yourself, or workers to lead, as well as the problem of ecologically sound
disposal of the debris. OSHA is quite clear about lead abatment. I do not
suggest that you put the paint in a plastic bag and throw it in a trash can.
There are NPS Preservation Briefs available on the I-way that you should check
on the subject of paint removal.
Whatever you do, don't lick your fingers.
][<en Follett
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