AOkay, I'm making buttercream, super simple - butter, flavoring, and confectioners sugar. I have no problem with it separating until I go to use it and add food coloring. Whether its piping or frosting it separates. What am I doing wrong? Is it the food coloring? Also should I use meringue powder for a thicker consistency for piping rosettes on the side of a cake. Now they are falling slightly and look wilted....

ASounds like you might need to add more powdered sugar that might help the wilting not sure about the color separating though I have read on here that hot hands can cause icing to separate or that wilton food colors sometimes separate.

ADo you use liquid food colouring? If you add too much of that then it could separate, try using gel colours as they don't affect the consistency of you buttercream.

AHow much butter and sugar are you using?

AI have had issues with Wilton gel colors separating but americolor seems to work better. What are you using?