In article ,
DoN. Nichols wrote:
On 2010-09-20, Robert Bonomi wrote:

I've seen other suction-cup pads, like for holding soap on the wall by the
bathtub, or various kinds of wall-hooks, stay in place for *months*.

And I've seen them give way in a matter of hours. :-)

True. as with any tool, it works better if you use it properly.

And I've also seen a single lever-operated suction-cup stand
(works by deforming the middle of the cup -- no valve holes at all)
intended to hold dial indicators and other things for machinist purposes
let go of rather smooth surfaces in less than an hour -- when another
metalworking club member was demonstrating just how good it was. :-)

Of course, you don't want to use soapy water on ground steel. :-)

True. Anything with a relatively low surface tension, to act as a 'void
filler' where the cup meets the mounting surface, will extend the grip
strength/duration _considerably_. As long as it isn't absorbed into the
materiel of either the cups or the surface, doesn't particularly matter
how 'volatile' it is -- the molecules 'doing the work' are in an essentially
'sealed' environment.