I use a lot of Kona solids. I treat most of the dark colors in Retayne.. Yes, red, black, green, blue, purple, anything dark. After soaking in Retayne, I wash with a color catcher. I have had all kinds of colors bleed including dark pinks, aquas, etc. I believe in being safe and not ruining a quilt. Fabric costs too much and my time is worth something. I don't want to ruin a quilt and my time by not treating my fabrics. This is of course MHO.