Naturtint vs. Herbatint
I have medium brown hair and probably like 10-15% grey, but they are resistant greys. My hair is wavy, meaning if I let it dry naturally it is frizzy but not necessarily curly. It is not flat but it's not really thick or course either. I'd say medium between fine and thick but a bit more on the fine side. I believe my hair is somewhat porous, except for the greys.
Anyway, Naturtint turns my hair into straw and also makes it very red and brassy. I have tried it several times, and tried different colors, never going more than 2 shades from my natural color, and always brassy. Either that or the dark blonde to browns leave it way too dark.
I always use the N, neutral colors because they suggest that in order to cover grey. I could mix an N with an ash tone to try and fix the brassiness, but because it is so bad on the condition of my hair I don't bother. It starts out a bit dry, and then each week it becomes more strawlike until I just can't even blow it out without it being total frizz, and that is even after using my straightening solution.
Herbatint is slightly better on the condition of my hair than Naturtint, but still brassy or way too dark if I used a dark blonde or brown. I finally got Clairol radiance today, a semi-permanent colorgloss that is NOT good for you but I just couldn't handle the orange, straw hair any longer. The toxic chemicals actually keep my hair in better condition. :( I am looking around for a natural semi-permanent to try, because maybe my hair just doesn't like permanent haircolor.