Glassware Collectibles

I use Rit dye on the stovetop and get exceptional colors and patterns in my home tie-dyes. The problem is, no matter how well I rinse (before and after removing the bands), by the time I use detergent to wash it, the colors bleed together, and tinge the white, so that the piece is muted instead of brilliant. Is there a pre-bath I should use to help set the colors? I've tried rinsing under running water, instead of in a tub, until the water runs completely clear, and this helps a little. Still, when it is washed, it bleeds onto itself and is no longer as attractive. If I hand-wash the piece and rinse quickly under running water, again, the colors still look nice, until it is laundered. I've tried heat-setting in the dryer and ironing the pieces before laundering a second time, but all to no avail. How do I keep my tie-patterns distinct and bright?