On Mon, 15 Jun 2009 11:55:58 +0100
Dan Smithers wrote:

RubberBiker wrote:
First off, disposable gloves are essential.

Ummm, yes.

Polyurethane glue works best in closely fitting, and firmly clamped
timber joints. Whilst it will gap-fill, the foam has no strength. It's
pluses are the strength of the joint where it is well compressed, and
that a good joint is truly waterproof.

Experience will tell you how much to apply.

That's the bit I was missing. I slopped it around liberally and was then
horrified as it expanded. A typical first time use mistake I guess.

On a good tight joint, you
will get some foam expelled, but you can take that off with a scraper
once hard, and then sand or plane the face - but I would emphasise the
good, tight joint.

What sort of work are you doing wit it?

I am repairing a wooden dinghy - pin and gluing a batten to strengthen a
repair. The underneath board is not completely flat so something that
fills the gaps is useful.

I did follow the instructions that said to remove excess with acetone
but in the end I did as you suggest and trimmed once hard. Next time
I'll try spreading it more thinly - a thin smear over the mating
surfaces and a little more in the gaps.

thanks

dan


I think for a boat repair you would do better with a two part epoxy,
used with a filler to gap fill. It will be interesting to find out in a
year or so how the polyurethane glue worked out in the long run.


I use poly quite a bit, I find you don't need more than a smear on one
surface (wet the other) for a well-fitting joint. I never wipe the wet
glue-foam up, it's better to take it off with a sharp chisel when it's
set.

R.