My buddy used to put his pipe in a bowl, fill it with enough iso to cover half the pipe, then cover it with a paper towel. He put this in the microwave for 10-15 seconds at a time. The alcohol has a low boiling point so it won't get super hot but gets hot enough to disolve all the resins. It will literally come out spotless in under a minute with no scrubbing. Try it, you'll be amazed.