I was reading in another post about the effects of caffeine and hair growth. I put some black coffee in a spray bottle and have used it a few times. I know that even if it would help promote hair growth that it will take awhile. However one thing I have noticed is it does darken up my existing hair making it look thicker. My hair is very thin on top and with gray in it.Some of it I would even call fuzz instead of hair. I just spray the coffee lightly over all my hair and let it dry. Makes my thin hair and fuzz look much thicker. I just leave the coffee in until my next hair washing. I have light to medium brown hair with some gray.
