Air trapped inside a can of wood stain or varnish causes the partially used portion to skin over and eventually solidify. My solution to this wasteful problem is to displace the trapped air with clean, smooth hard pebbles — the kind found in creekbeds. I just drop them into the can until the liquid rises to the can’s rim. Lid replaced, I’ve got ready-to-use varnish or stain the next time I need it.
Betsy Race, Euclid, OH