I know this doesn't help you now, but perhaps in the future it will.
Despite DMC being colourfast, reds and sometimes rich blues can still bleed. The same can be said for other brands or hand-dyed flosses. If you're washing a finished piece, use cold water with a bit of vinegar (about 1 part vinegar to 10 parts water) to soak the piece in first. Vinegar acts as a fixative, preventing bleeding and stopping dye from setting on new surfaces.
In your case, since you were trying to do a tea wash after the piece was finished (I think that's how I understood it), you WANTED the tea to set in the floss and fabric, so a couple of experiments to try would be:
Stain the fabric and the floss separately before you begin your project, doing a cold water and vinegar soak (rinsing with cold water when finished) after you've stained them.
Or, soak the floss in cold water and vinegar (rinse afterward with cold water), then stitch your project. When finished, tea stain the project, and your floss really shouldn't bleed -- although it likely won't pick up as much of the tea stain as the fabric will.
Good luck in future projects.
but I got confused by the mention of DMC's.
