FYI - I am a newbie so this maybe a silly question. : )

Is it possible to paint with the food color/vodka mixture on buttercream instead of Fondant? Obviously it would probably have to be a crusted Buttercream (I don't know if that is what it is technically called, but that is my termonology.) I'm really not a fan of Fondant but I really want to try painting on my son's 2nd Birthday Cake. Any opinions?

Oh, I probably should make clear that I don't want to paint big blocks of color. I'm looking to do a simple line drawing of the zoo on the sides of the cake.

Is this even possible???

Look at my skateboard cake and cow cake. Both of those are buttercream and I painted on them with airbrush colors. You can use the gel with vodka, its the same idea. Just have a light touch and don't press too hard on the crusted buttercream.