The recipe I use for buttercream it the 1/2 lard, 1/2 margarine, icing sugar, flavor and milk. I find that is doesn't flow nice. When I decorate borders etc, it looks rough? Any ideas?
Also, how do you stop colors from bleeding into one another? I wrote with white on top of brown and the brown ended up turning the white into a sand color? Same thing happened when I piped blue and white stars side by side.
Any help would be appreciated.
Thanks in advance! 
Is it lard you are using or shortening? Lard=animal fat, shortening=vegetable oil. I'm not sure about the bleeding problems but as far as 'rough' goes, sounds as though your frosting might be too thick. Here's a recipe I use, tastes great, very smooth, easy to pipe, and I never have a problem with colors bleeding.
http://www.cakecentral.com/cake_recipe-5183-2-My-Buttercream-Recipe.html
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