All those methods sound pretty good. It really depends on the extent you don't want to have a acetone logged stock... warm it up with a hair dryer first. Wrap it in the rag and wrap the rag in plastic around it... a plastic that will not react with the acetone it's nice if the rag is warm too. And then you just keep repeating the process. It is patience you start to do stuff too fast and you're going to screw up some grain or something