I wanted to try covering cupcakes using poured buttercream for a smooth finish.  Searched CC and found How Tos on it.  I heated my CB slowly as directly and it came out oily.  What did I do wrong?  Are you supposed to use a certain kind of buttercream?  Or should any work?  I use Winbeckler's Buttercream recipe.  I really need to figure this out in 2 days as I need to cover an order on Friday.

The technique works on buttercream that is not egg-based. Winbeckler's buttercream should be fine.

If it has gone oily, then you have overheated it.

The buttercream should be melted in a hot water bath, just until pouring consistency. Any hotter and it will split [become oily]. 

AThanks auzzi for your response! By a hot water bath, do you mean like over a double boiler?

bmmcleod:  Yes, I think they do mean a 'double boiler'.  Don't actually boil the water while you are melting things, you can turn the heat on low.   and Don't fill the bottom pan up so much that the hot water touches the bottom of the upper bowl.

Just let the steam from the hot water slowly, gently melt what is in your top pan.  Take your time. Good Luck.