I use color catchers when I wash my fabric the first time. If the color in the catcher is very dark, I will wash the fabric a second time and if it still is extremely dark, I may not use it. Depending on the fabric if is looks like the color is washing out, I won't use it. (I had that once with some home-dyed fabric I bought at a quilt show. And another time with some blue flannel fabric and it looked so distorted I should have taken it back to the store.) Otherwise, I am not concerned about it. When the quilt is finished, I wash it with a color catcher and usually give a few color catchers with the quilt with instructions to wash it in cold water and use the catcher the first couple washes.