Re: ][<en's,  "A 'good' cleaning job stops before damage is done, and
therefore the building may not
appear to be really clean clean."

I second that motion.  I always try to test each cleaning procedure to the
point of failure, and then back off a safe distance.  That way I know the
limits, and how how far it is to go over the line.  The ceiling to Grand
Central Terminal was done that way...just enough dirt left to know we
didn't go too far.  Part of that same lesson is not to try and "imporve"
the original finish.  If they left flaws in the original, I like to leave
the flaws in.  At GCT, if there were holidays in the original paint job, we
left them.  We only touched up where the paint had been and was found
missing.

--Jim