I haven't used black fondant accents on buttercream and I was wondering if they bleed onto bc frosting? I would appreciate your expertise. I love the effect of the black/white, pink/black but rarely cover the base cake in fondant.Thanks

If you peel them off you will see bleeding, but only where the fondant piece was. I've never had bleeding when the piece was on the cake.

Just make sure that it's secure and doesn't slip. I just put a little dab of whatever I'm using to secure it. Because if you put it all over, it could slip and leave marks. This advice is really more for fondant pieces on a fondant cake - when you are using an extract as the glue.