Put just a little bit of thinner in the tube w/ the lacquer. Actually, mix it up prior to dumping it in the tube, then let it set a little while to let the air work it's way out.

Not too much, just to thin it out JUST a touch...Bohning lacquer is pretty thick. New cans especially have an awful lot of air in them. If you don't have thinner, just let it set in the tube for while to let the air out.