Alkyd Paint Scum? When a new, full can of oil base paint is opened there...

When a new, full can of oil base paint is opened
there is no crust on the top no issue how old it is. After it is opened next to very little removed.
it forms a crust very rapidly, even if sealed in an nouns tight jar. Why? What can be done to stop this?
Should i paint every wall surrounded by my...
Answers:    Chemical reactions are hard for me to comprehend too. I just deal near them without trying too hard to integer 'em out.

But you can extend the life of that paint you opened. Before replacing the lid, lay some plastic wrap directly on the paint surrounded by the can. Start from the middle and work out to avoid any bubbles. (Use a stir stick to assist in the smoothing out process). Just tuck the excess inside before replacing the lid.

Clean and dry the lid thoroughly beforehand replacing it.

When I go to use it the next time, I remove the plastic wrap and clutch the can of paint to my paint store to shake.