Polurethane glue is a great all purpose glue. It bonds anything to almost anything else. Specifically for woodworkers, it will bond wood to wood, or wood to metal very well. It can be used as an interior as well as an exterior glue. Once it has cured, it is not affected by changes in temperature.
Another great benefit to polyurethane glue is that it is completely water proof. In fact, water helps it cure faster and stronger. The moisture content in the wood actually helps this glue work better. Otherwise, lightly spray the surface you are gluing with water to get a stronger bond.
Polyurethane glue has an open time of between 10 to 40 minutes. This is great when assembling a complicated piece of furniture. It provides ample time to get the clamps on properly and adjust them into position. It will take at least ten hours to cure completely, so it is a bit slow in this regard.
When polyurethane glue cures, it expands in a foam like manner. If you have never used this glue before, it is surprising how much it foams up. You should wipe off the excess glue as it foams up with a dry cloth or thinner.
I caution you to check up on your glueup every five or ten minutes for at least an hour to make sure the glue isn't foaming and running down your assembly. Otherwise, once this stuff dries, it is extremely hard to remove. It sands and stains well after it has dried, however, its best to get the runoff before, it'll save you alot of time.
Another caution about this glue is to make sure your joints are tight. Just because you see it foaming and filling gaps does not mean it is supposed to be used this way. In fact, it has no structural gap filling properties, as the foam is full of tiny air bubbles. Do not use this glue with biscuit joinery.
It's shelf life is a few years. When storing the bottle of glue, try to squeeze some air out, and keep it away from humidity and moisture.
Don't necessarily believe the hype about it being the strongest glue neither. This is just marketing. When tested against the strength of PVA yellow glue on maple blocks, the polyurethane glue faired about the same for strength.
Overall, it can be used on almost all woodworking projects like PVA glue can. It is more expensive than PVA glue so it is probably best to use it for outdoor or high moisture applications.
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| WoodWorkingAdvice.com Last page update: July, 2008 |
