"Swingman" wrote in message
...

"Robatoy" wrote

The cracking has a lot to do with selection. Natural fissures occur,
but can be found ahead of use.
Chip? Well, that takes a bit too. Something that chips granite, will
likely damage/pit cast iron as well.

Used two part epoxy to glue the wood "backsplash" on this 'kitchen desk'
last year:

http://www.e-woodshop.net/images/3811kit-11.jpg

A month later someone apparently hit it with enough of a 'shear' force to
knock it loose and chip the granite, leaving 1/4" deep pits where the glue
had been applied. The granite chips were still neatly bonded to the wood
and the wood was not damaged, so it certainly appears that the epoxy
indeed weakened the granite?

I doubt the epoxy penetrated the stone surface by 1/4" and compromised the
material. What likely happened is the material directly under the adhesive
spots failed in direct shear, as concrete would in similar circumstance. I
would expect to find 45 degree cones under the spots of adhesive.


Decided I didn't want to repeat the process, so I drilled 1/4" holes
through the granite and ply substrate under each foot, applied some
construction adhesive, and ran a wood screw into the wooden feet from
underneath. I figured a mechanical fastener would hopefully preclude a
future service call, and there have been no reported problems since (now
that that was said out loud, just watch the phone ring tomorrow!).

Depends on edge distance. The expected failure mode is still direct shear,
this time from the bored hole to the edge. The backsplash likely will now
fail first.


The question: what would *you* have used as an adhesive in the first place
if forced into a similar situation?

It isn't a matter of which adhesive. The epoxy held. The failure was in the
substrate, the granite. Approach the problem as though the desktop were high
strength concrete. How many anchors, how deep, how far from the edge, would
you use if it were concrete?