I tried a lot of remedies for my musty featherweight case including sun, Irish spring, softener sheets, etc. Nothing worked. I knew charcoal is supposed to absorb odors but I couldn't figure out how to use it without a mess. Finally, one day the light bulb went on. I got a set of Dr. Scholl's odoreaters shoe inserts -- the ones that contain charcoal. It worked! Mustiness completely gone! I have kept one of those inserts in the case ever since. Is the mildew gone? I don't know. However, all the odor is gone.