Hair dyeing question

[Phaestion]

I need to dye my hair black for a cosplay soon (I'm Spock okay) but I don't want to damage my hair.
Is there any way that I can get black/very dark hair without damaging it in any way? I'd also love if it would wash out in ~12 washes or less.

[Anje]

What color is your hair now? Blond hair tends to have more trouble with long-term staining than darker hair, so be sure to take that into consideration.

For something that washes out fast, I'd go with those hairsprays or maybe the Fancifull rinses. Both will make your hair feel awful and coated, but they're generally not known for lasting past your next shampoo.

The next level out while staying non-damaging tends to be vegetable dyes. Things like Manic Panic, Adore, Punky, etc. They'll stick around longer than 12 washes on most hair, though it depends on your hair, your current color, how damaged it is, etc. (I'm still waiting for some purple of this dye class I put in back in January to completely wash out of mine. It's faded a lot, but my hair is still looking more brown than red from it.) I wouldn't recommend this if you're blond -- there's too much risk that it might never completely come out. Edit: The dyes themselves aren't damaging. However, they often have instructions to bleach your hair first so they stick longer and are brighter. That can be damaging but it's unnecessary for what you want.

Henna + indigo is not damaging, but you shouldn't count on EVER being able to get it out. Don't listen to anyone who suggests it for anything temporary.

Finally, there are wigs. Cram all your hair into a wig cap and have fun. You probably can get a good costume wig (check ebay) of fake hair for $30-40. If your hair is light or has some past damage that might make temporary colors more likely to stick, this might be your best option.

[Phaestion]

For the record, my hair is a light brown. I'll look into some of the things you suggested, though. Washing out quickly isn't necessary but I'd rather it fade eventually.

[meteor]

There's a great article and thread on natural hair dyes by Nightshade: http://archive.longhaircommunity.com/showthread.php?t=51646