Running a bit of an experiment in that area as well. I took an empty container that held Ecotrin. Pretty heavy duty white plastic bottle about 3-4 inches tall, strong tight screw on cap.
Stuffed it with cottonballs and then saturated with alcohol. Wondering how long it would take for the alcohol to evaporate, if it does at all.
Thought it would make a good fire starter.
Only two weeks into it and the container has lost no weight, so I assume the cap is pretty air tight.