with partially used cans of anything- paint, varnish what have you. But, most any regular paint store, such as Sherwin Williams, will sell you a brand new quart can. You can fill that, THEN shoot in some propane and you should be good for a year or two.

As an aside, I just used some paint (Pettit EasyPoxy)I had unopened, still with the clips around the lid, that I bought in 1978!!! I for sure tested it, but it dried hard, like it was supposed to do. I painted a newly built dinghy with it. I was amazed!!