I am using small carbide burrs,   air driven     hand held die's with low psi
to remove hardened calcium deposits from large corinthian columns at a church;
I am able to control all and any part of what I am trying to remove without
interference to orginal; most sculpture supply houses have such tools...after
removal to your satisfaction ..then decide on your cleaning process for the
entire job.......by the way   which Parthenon.are we talking about....I had
the honor of going up on scaffold on the one in Athens in 85;(courtesy of US
and Greek gov) but then we bombed Quadaffi and I had to get out of Dodge
..leaving behind..a good many tools...and dalience's of romantic
nature.....but that Parthenon was free of calcium deposits ..it did have
bronze staining from its ancient anchoring system (if memory serves me
)..which were polticed off.
regards M.....
  you wrote     >.We have a cleaning problem at the Parthenon:  some kind of
calcium
deposits have formed crusts on the statuary in the east and west
pediments.  The material came from the leaking roof overhangs, dripping
through the concrete at hairline cracks.  There are no joints in the
overhangs, but water always finds a way through.  No cleaning chemicals
work, but our preference would be to soften the crusts, so that we could
gently wash away them away, without damaging the concrete or dislodge
any of the aggregate.  We are still testing.  I don't know if any of the
abbrasive systems can be controlled enough to remove the crusts, but
maybe we should begin looking at these systems, too. <