How much should I charge for Face painting?

Just wondering what you all charge for face painting at festivals ?as opposed to bday parties ? I have been doing henna for a few years now and recently expanded to face painting .Just this past weekend I charged 150.00 flat rate for a Birthday party then when i got there I was expected to paint 35 faces and then adults were lining up none of the clients tipped ..I ended up busting my hump for several hours and ended up using up alot of my good/expensive paint at the end of the day I made little profit for my efforts ...Any advise or thoughts ?

Charge "by the hour", not by the party...Reserve their appointment time with a retainer fee. The let the client who hired you know a little before you close up if there is still plenty of guests unpainted. If you don't have a back to back appointment, & know you are available, ask if they want to extend at $___ per half hour/hour or whatever increment.

Don't expect the guests to tip, but the hostess/client most likely will if she's happy with you.

If it's not possible to extend/you don't want to for whatever reason (they're using you as a glorified baby sitter/the adults are trashed/the children are all using words you never heard until after you were married), you're good to go, with "I'm sorry I have another appointment" (--with my other sane self, to make a phone call, whatever...)

thanks so much for your valuable advise !

I charge per hour and have a 2 hour minimum. I explain I can paint 5-15 kids per hour. If there are only a few kids, I will do more detailed work, do adults, and repeats (additional design to the arm or whatever.) If they have a ton of kids I'll let them know that it might take longer and would let them know at the party if I will be going into more time.