How to keep air from getting to polyurthane stored

I seen to always seem to lose about half of each can of Polyurthane and Tru Oil because of air in the can or bottle! I seal the can , but the air collected in the can makes it harden. Does anyone know of a way to get this air out of the can? Thanks for your help. HHutch

[Bandaid]

Just before you put the lid on the can blow into it to dilute the oxygen which causes the material to scum up. Secure the lid and store the can upside down. If any scum does form it will then be on the bottom when you open the can. Not fool proof but it helps.

they also sell something called 'Bloxygen' that displaces the oxygen and keeps the paint from spoiling

I use a 2 inch finishing nail and punch holes all the way around the top of the can where the lid fits in. This does two things, the stuff that collects there from dripping off the brush goes back in the can and when you put the lid on from one side first it helps allow some of the air inside to escape from the can. It's not 100% effective, but does help.

[groozier]

I've heard that you can put marbles down in your bottle to displace the air in the container. I can't remember where I heard this, but it was probably someone on this board.
groozier

When repairing and refinishing golf clubs in the days of persimmon and laminated maple woods, dipping poly was the finish of choice. We used to buy it in gallon cans and tried all the tricks to keep it fresh. Some worked, some didn't. The methods we used were the finishing nail around the rim, Bloxygen, and there is/was a thinner available for the stuff. Can't remember the name of the thinner now, but will dig around and see if I can find it and/or a source.

[Mike-in-WV]

My wife gave me some containers that are air tight from Tupperware , I believe. You fill it and then press down on the center of the lid for a second or so and all the air escapes.Really does help keep it fresh. Mike

[Beattle_Bailey]

Really simple, actually....I put the lid back on and then tip the can over on its top for storage...no problems.

Need to be careful storing oil base products in plastic, some combinations will have a reaction that can adversely effect the stored material. Not all, just some.

Polyurethane tends to thicken in the can because it reacts, or oxidizes, with the oxygen that is already in the can. It's not really an evaporative drying process as with common paints. It's no problem with a full can or a nearly full can, however, as the can is used and there is more and more oxygen in the can the process becomes progressivly worse. The only solution is to get the oxygen out, either through minimizing the air space or displacing it with something else.