How do you prevent black cotton fabric dye from running?
There are a couple tricks you can use to prevent dyed cotton
from running; first is to make sure you are using very hot
(boiling) water to color the fabric, second is to add salt (rock or
table) in the concentration of 1 cup per article in dye bath.
When the material has reached the color you desire, soak the still
wet fabric in a fixative bath from RIT/TINTEX
or Aljo dyes. This should be available wherever you purchase