I am a fabric dyer. I never use the dye catchers. I use a tsp of Synthropol liquid soap. I wash dyed fabrics and batiks in hot. When the water comes through the hose and out of the washing machine, I have a small basin to catch some of the water to see how dark it is. When I am on what I consider the last wash/rinse, I throw in an old white sock to see what it looks like at the end. Naturally, reds will tend to bleed more. Most high end quilt shops sell Synthropol and you can get it online.