Harmonica cleanliness isn’t an issue of utmost importance, but to those who play, it can be difficult to master. Different classifications of the instrument require different techniques, but they’re nothing too complicated. If you can play it, you can clean it .
The benefits of playing the harmonica include the easy maintenance- it’s actually bad for your harmonica if you clean it too often. Most harmonicas will wear out before they need a thorough cleaning. Unless someone else plays it, don’t be over zealous with any cleaning method unless you want to end up with a new harmonica.
If you feel the need to disinfect, you can start with rubbing alcohol. Be aware that you have to rinse the instrument very well after cleansing it to avoid getting yourself sick the next time you play it. Pour the alcohol over the mouthpiece; don’t soak it. After you feel that you’ve rinsed all the harmful chemicals off of the mouthpiece, tap the harmonica against a soft surface to get any excess water unless you want to blow bubbles next time you practice.
Reaching the area under the reed plates will be difficult unless you want to take the whole thing apart, but it can be done. The only problem with that method is the reassembly process. You can’t put it back together too tightly (or too loosely) unless you want a distorted sound. Check the manufacturer’s instructions for putting it back together if you’re feeling confident. Buying a new harmonica is your safest bet. Hydrogen peroxide is the safer version of rubbing alcohol, and the same technique applies.
Chromatic harmonicas need more attention paid to them. Chromatics have a small button on the side of them and white plastic valves on top of the reeds. The valves are your wind savers, and you need to avoid displacing them when you clean. Chromatics also can NOT have water run through them or be soaked. That’s yet another way to guarantee a need for a new harmonica.
Cleaning the comb of your harmonica can be done with a small toothbrush and some warm soapy water, unless the comb is wooden. If that’s the case, stick with only the toothbrush and scrub gently. If the comb is metal, make sure you dry it completely. Rust will distort your sound, and its taste will make you want to change instruments.
Using polish to touch up the outside is a poor idea- there’s now way to make sure that all the chemicals are washed off after, and tarnishing won’t have any negative effect on the sound.