My wife is making a 9x13 cake and the fondant is not going black yet. How much color should she be using with the americolor super black?

Is she mixing the color into the fondant or airbrushing it on?

She is mixing it in.

also depends on how much fondant she is coloring. To get black when starting with White it usually helps to color it brown first, then add the black. Also if she lets it sit overnight the color should darken some.

Is it fondant she bought? or fondant she made? (wont' make a difference on coloring, but if she made it, it's easier to mix the coloring into the liquid before adding the powdered sugar - uses a lot less color and uses a lot less muscle)

It is fondant she bought from Toronto, McCall's.

It usually doesn't take much for me, but it does darken as it sits. It is good to color black the day before to it can set up.

She is worried because she said the fondant looks green and the cake has to go out tomorrow afternoon lol.