Verne Chesbro writes the definitive work on color separation.

Oil and Water, a plot thought to have been originated by Ed Marlo is the focus of and inspiration for this work. In it you will learn not only version of the classic Oil and Water plot but also many routines that can be performed in which random red and black cards separate magically.
Alex Elmsley’s Counting Four as Four sleight is discussed in detail as well as Bob Veeser’s Veeser Concept and Veeser Count.