Edwin Pawlowski wrote:
While reading up on granite installation, the
book indicates that granite and marble pros install with silicone rather
than mortar.


I have installed marble on the floors and walls of my bathrooms with no
trouble and plan to use mortar for my granite over a bed of 3/4" plywood
covered by a 1/2" layer of backer board. Should I investigate this
silicone thing further or just go with my original plan?



Nah, they wrote a book about what the pros use but I'd bet you know more
than them.



Edwin,

I believe the OP's question may be legitimate, and may be due to some
confusion about the different types of product(s) themselves. The
numerous counter top outfits in my area use silicone for installing
solid stone countertops over plywood, however most use a mortar bed or
backerboard for granite or marble tile installation on counters, with
thinset. I beleive it helps them achieve a more even surface over all
the tiles.

For granite or marble floors on concrete slabs some use a mortar base,
while some just prep that may include grinding or planing areas of the
slab to eliminate high spots, followed by use of a granite or marble
specific thinset which is able to better support the heavier stone when
setting.

The recommendation for some marbles (greens) are setting materials such
as those produced by the Laticrete Co. to eliminate the moisture that
causes spalling problems that traditional thinsets present when using
green marbles. Here's one of their recent additions.
http://www.laticrete.com/stone/310mixer.html

Be nice to know what book the OP is referring to.