JohnW,

I've been bagging wings with PolyU. Works fine.

If there's moisture in the bag before sealing it, there will be moisture in the bag when you remove the wings. In my experience, the moisture in the balsa is enough to kick off the polyu.

With regards to moisture and misting for polyu, I don't mist my balsa and I have not had any curing problems. If anything, misting causes more problems with the expansion of the balsa during cure, then warping afterwards.

Toymaker, I'm surprised that you need to mist in TX. I bagged a couple of wings this winter in my very dry basement, and didn't seem to have any problems.