True, but I will be resisting the cross-over event as much as I can! Trying to not do anything that will speed it up. If you are saying that when you are called, you go, I am telling them not yet. 
Interesting. Black paint to get “white” (frosted) image and white to get “black” image. Who would have thunk it? I assume you paint the back (inside) of the glass??? Yup, newby here.
Nope, paint the outside.
That’s the thing. Tempera used to be a brand name. Now, everybody and their uncle are making it, and you can’t be sure of what’s in it. And the fact you may get acrylic changes everything. 
OP, did you ever figure this out? I’m having the same issue.