Will polyurethane glue cure in a vacuum bag?

[greyhound flyer]

A question for the baggers out there-

Does polyurethane glue (Gorilla, Elmer's, etc.) cure under vacuum? Was wondering about sheeting foam cores with wood and using polyu for the adhesive instead of laminating epoxy.

Thanks,
--GF.

[bigandy]

I know PU glue cures by a reaction with moisture. It works when exposed to the moisture in the air, so whether it works in a vacuum is debatable.

I would say that it probably will, especially if you give the surfaces it is bonding together a light spray/brush with water to dampen them (allowing the glue to cure when the atmosphere, and therefore atmospheric moisture is removed by the vacuum).

Probably the best way to find out if it works for your application, is to try a small sample, and see how you get on!

Cheers
Andy

[ImaBiggles]

Yes PU will cure anerobically - it will foam lots more in a vaccum bag. I suggest mixing a small amount of water (~5-10%) of glue volume with the glue before application - that water will drive the cure.

[R. Carver]

Ditto on the yep-I did it on my Jim Young B-29 wing. Seems to be a bit heavier than a nice thin coat of epoxy, though...but I could be wrong.

[evan]

It will.

Gas is formed as the curing progresses (ask me how I know) so a continuous or vacuum regulated switch source is in order.

To try to keep it light; put some PU on the wood, spread thoroughly and scrape-off with an old credit card (you need the new one to buy more stuff), moisten foam with water and wipe excess with a slightly moist rag and bag.

I dont know if it's any better than epoxy but I like it for wood sheeted foam cores.