I just wash all my fabric with my reg. laundry det. I'm not sure if this is what you are talking about.
You can use Retayne to prewash your fabric in - Retayne actually SETS errant dyes so they'll stop bleeding.
Synthropal "floats" out any unfixed dye and keeps it from "fixing" itself onto areas of the fabric that you don't want to be stained.
You can also use color catchers by Shout when washing the material.