Now that I have achieved/maintained phenomenal length (btw: thanks everyone, for 2 years of advice), I would love to accent it with a lighter shade. In the last 2 months, I've tried 2xs to lighten my naturally dark brown hair to an auburn, with no success. I'll get that shine & silkiness, but literally no color. I'm unwilling to leave the color mixture on longer than the recommended 20 minutes for my relaxed hair (African Pride/no lye). Is it possible that my hair is resistant to coloring?? I'd appreciate advice from the color experts on the board. Thanks so much!