How do you clean a mouthpiece?
What do you do for hard rubber mouthpieces that turn drab olive in color? Here's the answer from Tom Ridenour:
Get some good black shoe/leather stain (not shoe polish). Apply it, let it dry and then rub it down.
The rubber does not change colour. The black dye leaches out; natural rubber is white/ivory coloured.
NOTE: I have not had good success with Tom's method. Professional repair shops have buffing wheels and black buffing compound that seems to work better. Soaking a mouthpiece in bleach has also been suggested, and seems to help a little bit. I would like to hear of other methods.
More recently I have had some success for a 3M product for restoring the lustre to plastic car headlight covers. It is 3M Plastic Cleaner and Plastic Polish.