Harmon Mute can be written in 4 different ways

Above you can see the use of a “Wah” effect, this can only be achieved with the stem in and is noted by writing “wah” or you can notate the closed (hand over stem) position with “+” and open with a circle “o”. To notate a gradual move between the two you can add a dash.

For example “+—————o” would indicate a move from closed to open over a period of time.

Harmon mute can also be written as stem out or half stem (out as far as it can be).

Harmon without stem is very quiet so shouldn’t be written with thick/loud scoring if it needs to be heard. This quiet, mellow, “buzzy” sound makes it a very popular mute option in Jazz

While it is possible to do a wah effect with a harmon half stem, many players will not be able to reach the end of the mute and not standard.