Vacuum chamber + polyurethane -- a hare-brained idea?

[roger wiegand]

Perhaps use a catalyzed polyurethane to speed the curing process? Won't be reusable but in a vacuum bag you may not need so much. If the solvents are indeed volatile they should pass through your vacuum pump; it's corrosives like acids that do them in.

[robert baccus]

Yes. Liquid poly,s are solvent based and must have good air circulation to cure.

[Mike King]

It won’t cure in the vacuum bag. So, what are you trying to achieve by putting it in there?

[Dave Bunge]

What about using sanding sealer first?

I don't use wipe on poly very often. Mostly I use Minwax Antique oil, which is an oil/varnish/solvent blend that I wipe on then wipe off excess. But I've found that using sanding sealer greatly reduces the number of coats of AO required to get a good finish.

I use Zinsser Seal coat, which is dewaxed shellac in denatured alcohol, I believe a 2 lb cut. I dilute it 50% with more denatured alcohol. I sand my bowl to 320 grit, apply a coat of the diluted sealer, let it dry and apply a 2nd coat. If there is excess sealer (puddle in bottom of bowl), be sure to wipe it out and not let it dry. Too much shellac on the surface will gum up the sandpaper. Once the 2nd coat is dry, finish sanding and apply coats of Antique Oil.

This works well for me, doesn't change the appearance of the bowl from what I can tell. The sealer is much faster to apply, only takes a couple of hours to dry, and the DNA solvent is much friendlier to use indoors than the mineral spirits in the AO. Those are the reasons I like to use it.

Dave