Don't know about dichromate, but I just tried hydrogen peroxide. Some web reading suggested that it's oxidizing ability was enhanced in acid solutions. I only had 3% stuff around (drug-store H2O2), so here's what I tried:
Originally Posted by holmburgers
100mL 3% H2O2
~1mL 40% citric acid solution (this is about 0.4g).
It created a just-noticeable lightening of the dye stain in an all-white area (drop test) after about 90 seconds contact. Perhaps if you can easily get your hands on 10% or stronger H2O2, it might be a viable option, and one that eliminates the need for potassium permanganate.