I used Rit liquid to dye my tuffs blue again. They were very faded and came out great. Threw in a box of salt, kept the water hot and left them in there until they reached the color I wanted. Easy.
Before..........
During.......
After.....
Nice results but the salt would have been a waste of time, salt is used when dying cotton only, also if you have any metalic objects connected to the nylon it rots like fook, I experimented with dying seats tried salt with one lot and it badly pitted the bottom of a stainless pan.
I contacted Rit and they said salt is only for cotton and the dye is only designed to work for 40 mins max , after this time if there are no results it will never dye.
for best results warm a pot just under boiling, add dye liquid or powder , stir and add 1 tablespoon of non bio washing powder, add the item you with to dye then 40 mins later rinse with clean water.
You can also put the items in the dish washer first before dying to give them a deep clean