I like to prewash my fabrics, both to pre-shrink them and to avoid any surprises from bleeding dyes. I knew there were several chemicals that could be used in the wash to prevent problems with dyes, but I could never remember which one to use when.
Synthrapol is a detergent that washes away loose dye particles. Hand-dyers will use it as a final wash to remove excess dye. This is the product to try if you have had one fabric bleed into another – often times it will remove the ‘bleed’. Also use it when washing something where you think a fabric may bleed into the others. Or use Shout Color Catchers – they are similar to fabric softener sheets, but go in the wash, and help to pick up stray dye. (An added bonus to using the Color Catchers – sometimes they turn out to be the prettiest colors, and can be used in art quilting or craft projects!)