will royal icing decorations soften on top of buttercream? can i place them ahead of time? how much ahead of time ;)?
I have used royal decorations on b'cream w/o problems. It depends on what the piece it - how thick is it & such. The bigger/thicker the better. Also be *very* sure the piece is completely dry.
You want to place those decos as close to the p/u time as possible. They might soften some but I've not have any melt into a puddle :)
Depending on what the deco is you can put it on top of a sugar cube or pipe a spike of royal on the back that you push into the cake allowing the décor to not actually touch the b'cream but be just above it. Other people have said they make the royal piece on a backing of wax paper or plastic wrap.