Hi Everyone,
We have a contract to clean and hone the limestone framing around the
entry and windows at a church.  The Limestone has been damaged by
water.  What this means and what I see is fine (and not so fine)
etching from water, ingained white efflourescence, discoloration of
the limestone itself (from iron oxide perhaps?) and general soot.
They were unhappy with a "skimcoat"  test-painted on - (probably R-97
by Cathedral Stone Products).  Also, someone else tested Prosoco 942
and that didn't work either.  I tested honing a portion of the wall
with 400 grit Twister/velocity pads on a hand-held and using NCL
Hurricane natural stone cleaner.  It came out looking pretty good and
gave it a nice smooth surface. My three questions are:
1. Any other cleaners that I might try?  I have some Klenztone
Limestone cleaner that might do the trick.  I think I want to stay
away from acidic solution.
2. We are going to be working up high on heavy duty scaffolding.  I
want to work out a way that chemicals and water don't spray all over
the place and that the solution can be collected in some fashion.  The
windows will be cleaned professionally after we are done.  We will put
plastic, paper and tape around.
3. I am pondering getting a variable speed angle grinder with a water
feed (maybe the Alpha variable speed polisher), but wondering if it is
worth it.
We haven't spent much time working up high on walls.  So any
suggestions would be great.  Thanks,
Baird