I was cleaning my travel-tube the other day but all I had was 50% rubbing alcohol for wounds. I tried it anyway with just the rubbing alcohol and it had a hard time getting the built-up resin of the sides. I poured in some salt to act as an abrasive and this is what happened: The water sunk to the bottom and the alcohol to the top. The alcohol it what disolved all the resin that is why it is brown. The actual pieces of resin floated in-between. My guess is the water disolved more salt than the alcohol causing it to become heavy and sink. The top part was much purer than 50% after separation.