Henna doesn't touch my silver roots. It's strange, because the rest of my silver hairs, it turns this really pretty orangey/copper. But right by the scalp, it will not dye it. I even reserve some henna to use later, and I paint on the henna onto the roots and leave it on for several hours and wash it off. I do it a couple times. But the silver roots won't accept the henna.

Any help?