Polyurethane glue

[doug748]

I have just got a tub of polyurethane wood glue, Never come across this stuff before, is it any good. Said to be Waterpoof (inc seawater), Acid resistant, Quick drying, Gap Filling and Overpaintable. In use, it reacts with moisture and foams up a bit like...er..polyurethane foam.

 

[Poignard]

It's very good. Strong and easy to use. It foams up so parts need clamping together otherwise it will force them apart. Like epoxy it will fill gaps but does not maintain strength across the gap. Any residue is easily scraped off when dry. Wear gloves because it makes your fingers go black for a few days.

Unlike epoxy [which seems to keep forever] it doesn't keep very long once opened, maybe a few months then it starts to harden in the bottle from the outside inwards although you can always excavate and get a bit more out.

 

[30boat]

It's a very good moisture cured glue,I use it all the time.But it needs a fine glue line as it's not gap filling and it degrades in sunlight so the wood should be protected.It's also very messy so wear gloves ,it stains the skin like nothing else.The foam is very easy to remove,but you shouldn't try to wipe it off wile still soft.Allow the glue to cure and then cut it off .

 

[Danny Jo]

[ QUOTE ]
Quick drying

[/ QUOTE ] Yes, and you must ensure that the surfaces are brought together before the drying starts. Always assemble dry, drill holes, and prepare clamps before applying glue. I get the impression that it cures slower when cool, but at low temperatures it's very viscous. For complex assemblies, get the slower curing variety.

 

[andrewbodenham]

Balcotan make a variant containing reinforcement fibres which is more forgiving in a less-than-perfect joint. They also have a variety of open joint / curing times available. Much of the stuff readlily available is aimed at the building / DIY market and goes off in about 5 mins, which doesn't give you much time to get things lined up.
Be aware that the adhesive is very slippery, so it's easy for parts to slide when clamping up unless mechanically interlocked. Does help though when assembling tight joints!
Sunlight degradation is confined to exposed surfaces and does not migrate into the joint line.
It does go off in the bottle, so cartridge guns are are a better bet. A bit of gaffer tape over the end of the nozzle keeps things moving. Sometimes.