has anyone heard about this method or possibly tried it and had good results?

I read that adding vitamin c powder to vinegar and a little shampoo then applying to the knots for an hour can lighten them significantly.

I'm going to give it a go. I'll report back once I've tried.

Interesting idea Idlewide. Please let us know how it turns out. And let us know if the smell of vinegar stays in the hair.
Thanks,
John