Thanks very much ladies. I may just throw it out or try it in a gloss (I hate to throw it away!). It's surprisingly hard to find anyone's actual experiences with this. I'd looked on mehandi before, and the forums say to discard leftover indigo, but nothing really about henna/indigo, and no real account of what would happen if you did use it. Oh well...it's probably best to throw it out b/c yeah, I don't want to turn my hair a funny color. :/