Ok,
I have been wearing a full cap for over 10 years now. Lately and in the past when I color the unit , the stuff I was using left it a bit dark. It was passable but I would spend the 3rd and 4rth month with my unit in a " its ok phase". So about 6 mo ago I started trying all the different coloring agents out there from all different companies. I work at a nutrition co so I was trying to find one with as little or no chemicals as possible.
I found the gold. It is here. I do not work for these guys. Note: If you are dying your hair darker get a shade about 3-4 times lighter then your desired color. It took me 2 tries as I ordered my hair match but it was to dark when i finished coloring. I am medium brown. If you get a medium brown it will go to dark. Last night, I tried the golden dark blond and it hit the perfect medium brown that I was looking for. No damage to the hair ! ! !

http://palettebynature.com/
The result is a new, 100% natural plant based permanent patent pending hair colorant that is free of: paraphenylene diamine (PPD), PTD, PPD derivatives, resorcinol, m-aminophenol, p-aminophenol, toluene- 2,5-diamine, azo-dyes, diazo-dyes, disperse dyes, ammonia, and parabens – all synthetic chemicals which are known allergens and suspected carcinogens.