I looked online and found a DIY color catcher using a solution of washing soda. The directions I found: put a tablespoon of the dry soda into a cup of hot water until it dissolves. Put in a yard of white junk fabric, or ratty toweling, and let it become saturated. Damp not dripping. Let it dry. Cut off a piece and wash it with your bleedable fabric. The soda ash grabs and holds the dye.
Has anyone tried this??