No black hair does not exist because black hair is just very dark brown hair unless your hair is jet blue that is when it is in the sun it has a tint of blue and your hair looks black in the daytime.
First you want to spray only three inches of your hair, quickly brush it than spray that three inches with hair spray once more. Repeat until entire head of hair is sprayed/brushed.
Lack of some minerals and/or vitamins, well if you have a comb i would sujust you move to a different kind of brush i used to use boreing old fronisie now that ive switched to loconvigouse it has...