Temporary Tattoo On Scalp To Conceal Thinning Hair

[pbaldi]

I have black hair and light skin and I've always used hair fibers to conceal my thinning hair. One time I lathered my scalp with JustForMen hair color and after I washed it off it had darkened my scalp and really helped with concealing the thinning. I just don't feel comfortable using that stuff too often as it might have some bad chemicals in there. Has anyone tried any temporary tattoo ink like Inkbox or some kind of henna to achieve similar results? I think they would last longer too. would be perfect to use on a vacation where you'd go to the beach or a pool because any other concealer would just wash off.