My roommate told me that if a light-haired person dyed their hair dark brown or black, their hair will grow out darker than it was before dying it, and may never return to the original color. I am a bit skeptical. Then I asked her if the light-haired person dyed it their original color or some other light shade, if their hair would grow out to be the original color again, and she said she didn't know.
She knows a lot more about beauty secrets, make up, skincare and hair dying than I do, so generally I trust her, but I don't see how this can be back ed up with science. I think if anything, people's perception of the original haircolor changed, or something.
Is any of this true? Pictures of before and afters? What's the scientific basis for this hair phenomenon?