White vinegar will do the same as a dye catcher. It will keep any running colors from being absorbed by the other fabrics and it will also help "set" the colors.
Just pour some into your wash load. I tend to wash my new fabric together, not with my clothes, so if I have a big load I use a couple cups of vinegar, a smaller load I use less. It all gets washed out so your fabric doesn't smell like vinegar when it's done.
Before color catcher, white vinegar was what people used.