In Reply to: No, they don't "need" one but.... posted by 4thetinlids on Thursday, 23. June 2011 at 13:37 Bali Time:
tell you anything about a possible reaction to para-phenylenediamine.
"Don't do a skin test with PPD "black henna". Your skin might not react to PPD the first time you use it. Since the reaction can take three weeks or more to show, or in some cases appears only after a second exposure, it is not safe to assume that a 24 hour skin test is going to tell you if you are sensitive. It will only make you more likely to develop a sensitivity. Just don't use it at all! "