Dyeing is a difficult problem. I prefer the Rit dyes, and use their "whitener and brightener" on many of my clothes, especially the riding britches.
To dye lycra/nylon/spandex, I always buy a dye that says it will dye polyester. Some dyes don't adhere to the nylon or lycra. Some dyes that dye cotton will not dye the lycra in a cotton/lycra garment. Go figure!
I always double or triple wash the garment after dyeing it. I try the cold wash, or vinegar wash, etc., but the dye continues to fade. If you're wearing the dyed garment with anything special, be sure to interpose a layer that protects the garment.
balletboy[/i]