Chris
The telescope from here at the edge of the  Delta is lucky enough  if I can
pick up Mrs Gilhooy sunbathing let alone look at the Stiener school over at
E.79 st; but my guess is that the super and the in-house architect decided they
could do the job ;
....if not you may want to look for the "sample" provided to the owner
somewhere at street level near the return;  which reminds me if Steve or Mike want
to pipe in ..
Im in process of following up a botched cleaning job; what I think got used
was Restoration Cleaner  "ON LIMESTONE"...anyway  you get the picture ; whats
the easiest best way to test for salts or residuals;
 Im thinking hot water at 900 psi is enough to flood the substrate what-cha-
think ?
Michael

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