(I beg to differ with you....vinegar works very well for me....I would rather use something 'natural' than a chemical.)
vinegar may soften & freshen your fabric---but it does not set today's dyes- the dyes were changed way back in the 70's by the EPA & what ever other agencies were involved- vinegar & salt has no effect on commercially dyed fabrics- now, if you dye your own fabrics with natural dyes they may help- but no effect on anything commercial-sorry
if you choose to use a color catcher you should re-wash with a new one until no more color is collected.
synthropol in the water will suspend any dyes in the water- keep them from getting on any other fabrics- Retayne (or Rit Dye Fixative) will set dyes- stop them from bleeding
batiks tend to have alot of (excess) dye- some hand dyes do to- they just were not rinsed well enough in the first place- once the excess dye has been rinsed away they will stop bleeding (or should) wash until no color is in the water....