"Robatoy" wrote in message
oups.com...
On Oct 19, 1:24 pm, Frank Boettcher wrote:
hey what kind of silicone do you use for the seal between an
undermount stainless steel sink and solid surface?

This kind of advice costs money.

I recently used some GE silicone II window and door for a little
outdoor project and it took it about ten days to cure. Stayed
literally gooey for that whole time. Kind of got me concerned about a
sink that can't be out of service for that length of time.

I use Gutter And Flashing (awning) Silicone II (GE). It sticks to
metal better. The clear is best.
The stuff DOES expire, so keep an eye on the date. Also, make sure it
is very clear and runny, and not cloudy, milky and rubbery. It has to
feel wet. It helps if you buy it from an outlet that you know has high
turnover. The fresher the better.

It was very, very hot for the outdoor project, but I thought that
would accelerate not slow down the cure.

Sure sounds like a bad tube to me.


Also, do you pull up the clips to almost there, give it a little cure
time then pull up the balance, or get it all at once.

That depends on how flat the flange of the sink is.
I tighten them, but not in a nutso-cuckoo way. I try to use a
sequence, a bit at the time, give the silicone a bit of time to
escape. (I use small blocks of MDF, hot-melted in place on the bottom
of the countertop so the sink doesn't float all over the place.
I also make sure there is a nice bit of squeeze-out which I do NOT
remove until a day or more later.
Just a sharp Olfa blade pointing down to the sink edge and touching
it. A cord of dried silicone should peel off.
Don't try to remove it wet....
Under the counter, I smear the silicone all over the bottom of the
flange and deck, almost like an undercoating.

Make sure you clean and clean and clean the metal on the sink flange
with methyl hydrate and 200-320- grit sandpaper...careful not the
scuff the shiny bits which will be exposed later.


Overtightening can create too much squeeze out. Neither surface is
porous, so don't think 'wood' as you clamp. A standard double sink
will use 10 -14 strong clips. It is said, that the silicone alone will
hold the sink, and the clips alone should as well. The combo, double-
good.

The adhesive is strong enough for big aquariums (ia?)..but they keep
things nice and straight and clean.

You owe me 2 cents.


Thanks for taking the time to provide an excellent answer. Advice like
yours makes this site extremely valuable.