No disrespect intended regarding the previous responses, but toothpaste (not gel) includes a very fine abrasive that will leave small scratches in the key surfaces. Some window cleaners include ammonia which can harm the key surfaces as well. The sweeteners used in toothpaste and the ammonia in window cleaner can harm the circuit boards inside the instrument. Specifically, if any of that liquid drips down between the keys and works its way into or under the key contacts, you will have problems. I use and suggest Cory KeyBrite. As an alternative, Key One from Music Nomad.

Cory KeyBrite




Music Nomad Key One