I've used it before. I put the cake in the fridge to let the SMBC harden and then put the fondant on. i had a problem with condensation but some people on here have done the same thing with no problems at all.
HTH 
Thats the nice thing about fondant. You can have any flavor of buttercream and still get a white cake on the outside if you want to. If you are in an area with high humidity, make sure you dont put too much of the ibc on or it will leak from the bottom of the cake.
awesome!
so do i still need to crumb coat and then put another layer of imbc thick enough to hide the "imperfections"?
we live far west texas so i don't think humidity will play a big factor!
i just saw warren brown's youtube video on making imbc...wonder if i can pull it off considering i am just a cake hobbyist. should i make a trial run of the imbc?
thank you all for you input....! 
If you've never made it before, then you might want to practice a couple days ahead of time. Good thing is, if it comes out right the first time, you can simply wrap it up tightly and store it in the fridge. When you're ready to use it just let it come back to room temperature, put it back on the mixer, and then beat the hell out of it with the paddle attachment and it'll be ready to go!
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