How to label mouth calls?

[Pocono_Mtn_Yelper]

Hello Everyone, question for the call builders out there. I'm fairly new to building diaphragm calls and was wondering if anyone had a proven way to write on or label mouth calls? Special type of pen or marker that will last?

I want to label them so I know which ones I like best, but can't find any threads about a marker or pent that won't come off with use. Any advice is appreciated!

[GobbleNut]

I have always just used a regular old pen to mark my calls on the tape if I wanted to label them and I haven't noticed any ill effects from the ink.  A pen will write on the tape fairly easily if it is dry...not so much if wet.  You may need to re-mark the calls, if needed, as the ink fades from being in your mouth a lot, however. 

I have not tried using a permanent marker like a "Sharpie".  I suspect that would work better than a regular ink pen, but I'm not sure that the ink type used in those would not be toxic to a degree. 

[Lonehowl]

A fine sharpie is great but it will fade eventually like anything else.