Hi-- I'll be doing the cake for my daughter's wedding on a Sunday in May. Since I'll be otherwise occupied much of Saturday and the cake will have to go to the restaurant on Saturday night, it needs to be mostly finished on Friday. I want to do a buttercream cake with molded lace borders and medallions--have never done that before. I've heard that fondant appliques will sag or slide off buttercream. Is this true? Could I make the pieces in gum paste and dry them to the correct curves on the cake pans earlier, and then apply them on Friday? Or if I did the long fondant borders ahead of time, could they be rolled up with a strip of waxed paper and refrigerated in plastic? And when it's cake cutting time, if the server removes the borders and medallions, will the buttercream icing stick to the back of them and come off? Thanks for any answers!
First, I am not a professional but will answer what I know. I have made a few buttercream cakes with fondant decorations and the decorations did not come off the cake, sag or slide down (which was a big fear of mine when I did my daughter's birthday cake. Her cake had fondant flowers all around both tiers). I let the buttercream crust somewhat and then put the decorations on the cake. I know that some decorators use a little water on the back of the fondant to get it to stick. I have done that and I have also stuck the fondant decorations directly into the buttercream.
Hopefully, one of the professionals will see this and can better answer your questions.