Will black fondant bleed onto white BC if left on overnight?
I think if it's not going in the fridge it will be fine.
I made a little penquin using a white fondant "ball", and wrapped it with chocolate fondant which I had colored black. It didn't bleed at all. I never put them into the refrigerator. Hopefully that is helpful? =)
I used Satin Ice on a zebra cake with real buttter buttercream. It was out all night and was still perfect the next day for the shower. Hope that helps!