Acrylic paints vs. bottle lids

A smear of petrolium jelly along the top of the rim and threads of the glass or plastic bottle will keep the paint from sealing the lid on even if the paint dries. 

 It will also work with tins like Humbrol paints.

I've used thin plastic sheet stock, (Evergreen,) easy to mark to proper size, then use a compass with sharp blade for cutting through. Also, many packaging containers are suitable for the same. The thinner, the better.

Have tried Saran Wrap, aluminum foil and others, but they seem too thin to allow a reliable compression seal, and they are pretty much a one time use.

Patrick