I just soak my glass pipe in a drinking glass full of 99% isopropyl alchohol for 24 hrs and it disovlves everything right off, then just rinse well with water and let dry.
To get 99% you usually have to ask the pharmisist for it becuase its behind the counter but they never ask questions. If they ask tell them you use it to clean computer electronics, which it is used for alot.