Saw this on tv- If you are attempting to store a half open can of POR. Fill the top of the can with a heavier than air gas such as butane or the argon from your welder. The gas will sit in the top of the can above the paint. Put a plastic bag on the top of the can then put the lid on.

The heavy gas keeps oxygen from hardening the POR. The plastic bag keeps the top of the can from gluing to the can.

To add to that, maybe trying a double layer of plastic. The top layer may stick to the paint on the lid and the bottom layer may stick to the paint on the can lip but the two layers wont stick to each other. If you use just one layer then each side can still stick to the lid and can lip and you will still be stuck.

Wax paper between the can and the lid. Place can in the refrigerator. Will last for a while... Just don't shake, be sure to stir when reusing.

You can put the remainder into a smaller can to minimize the air in it. Then do as the others suggested.

..... ...I had a can turn into a brick after 5 mths of storage(brand-new)
don't touch the stuff no mo'

..... :Doublle Trouble.....

Use the small cans (I like the 4oz sizes). A small can will actually go a long way. If it goes bad/hardens, then not much is wasted. I use ziplock bags when I reseal (two layers of plastic like mentioned above). I like the idea of the inert gas.

Richard

I also almost always use the small cans. If I am going to try to re-use a can of POR I drill a hole in the lid and dribble it out on the brush instead of prying the lid off. I use a cork to reseal it. I don't know if it helps, but the point of this is to minimize exposure to air.

Yes and especially humid air. Not too good for us here Shuie but a little better for those in the south west states.

Store the can upside down. This way it starts hardening from the bottom.