the only thing i've used is the wilton bc recipe.
what exactly is royal icing?
Royal icing hardens like candy...pretty quickly as a matter of fact. It used to be used on the "original" wedding cakes which were fruitcakes. But nowadays it's just used for decorating.
The best recipe I have found for it is in the Wilton books....merigue powder, sugar, water. Very simple. You can make all sorts of stuff with it being that it dries hard.
You would not use this in the same fashion as buttercream.
That's the recipe I use. Merignue powder, powdered sugar, and water.
It's not something you'd cover a cake with. It's not what I'd consider really eatable. You wouldn't be able to cut the cake either. It gets hard as a rock.