To set tie-dye, soak the article of clothing in water mixed with 1 cup of vinegar and some salt. To stop colors from running, use 1 cup of vinegar in the washing machine.
Some dyes used for tie-dying do not need to be soaked in vinegar, salt and water. These dyes need to be placed into a plastic bag overnight and then rinsed thoroughly the next morning. During the rinsing process, begin with warm water, and as the water becomes clear, change the water temperature to cold. Other dyes can be rinsed out right after the tie-dying process. Be sure to read the dye instructions prior to starting the tie-dye project.