Henna is not supposed to be black (here is a resource that answers quite a few questions about henna: http://www.hennapage.com/henna/ppd/index.html). I learned that henna is not supposed to be black during a recent, local international culture fair. A henna tattoo artist was there and so my children and I all got tattoos (they last about a week). During the application, the tattoo artist implored me to NEVER use Black Henna because it is poisonous and contains harmful irritants. She added that if I did use Black Henna I'd likely get terrible skin issues. This kind woman's advice coupled with website information I've found have convinced me: folks, stay away from black henna on your skin and hair.