In a message dated 5/11/2014 2:24:09 P.M. Eastern Daylight Time,
[log in to unmask] writes:
In
many, if not most, instances, the visible tile on the lower surface of vaults
(what I recall RGCo calling “soffit tile” on their drawings) are built
integrally with the subsequent layers of tile. So, in a way, they are “wedged”
in place like voussoirs. There are exceptions. Tile below the gross domical
form in RGCo’s vaults -- think of the vaults in the Oyster Bar in Grand
Central, as one example -- were applied to the “structural” tile in the manner
you describe. It is likely, though I have no documentation to support this
statement, that the elaborately decorated surfaces of vaults (the Nebraska
State Capitol comes to mind) were also applied to the surface of the
structural tile above.
Derek, as always, thank you. I posted this
query after seeing the Guastavino show at MCNY. There they have a
demonstration dome, perhaps 4' square, which indicated to me that the bottom
tiles were held in place only by some adhesive. Having just seen a
sofa-sized piece of cast stone fall from the Zeckendorf apartment house (c.
1985) at 86th and Lexington (apparently an attachment failure - no one injured)
it occurred to me that I have never heard of such a failure with Guastavino
tiles. And there are so many of them.
So ... what is that glue?
Christopher
(PS If you're interested in G as an architect, you
gotta see these photos: