Woodreaux, It takes two screws. One for the finish to exit and the other to keep the presure equal to atmosphere. Replace the screws promptly before much air intrudes. The stoplose bags look like a really good solution. Can we google up a source?
I just don't buy this method. I can't remember if a particular type of screw was specified in the other thread, but even if it were possible to keep a partial vacuum on the inside of the can when replacing the screw, which it's not, a screw through the lid of a can is not going to be air tight. Even the slightest vacuum, from the removal of a bit of finish, will be replaced by air eventually seeping around the screw threads. Nature abhors a vacuum, and a wood, or machine, screw through a thin piece of sheet metal won't prevent the equalization of pressure, IMO.
My method has always been simple, though not perfect. Store the container upside down after opening, and reclosing. As the air goes up any film forms in the bottom of the container and doesn't hinder removal of finish next time. As I said, it's not the perfect answer, as you still lose finish to "filming", but it seems to help me.
I like Keith's idea of using some other gas to purge most of the oxygen from the container. If someone would package and sell one of those workable gases in an aerosol can, with the little red tube to stick in the nozzle, it seems like it would be a simple and quick solution.
The thing I see as an issue for me with the StopLossBags would be storage. They appear to have to be stored laying down flat, as I don't see how they could stand upright stably. It would require drawer storage for me, which I am woefully short on. I'd much rather keep the finish in it's original container if possible. It's flat bottomed for a good reason.