4-5 weeks on average, depends on if your going from light to dark (very fast fading) or from medium to dark (tends to last longer)
6-20 washes
Forever and Forever and Forever .
No chlorine does not last long out in the oppen.
a month or two
Depends on how many times you wash your hair.
It doesn't last very long, about the same as temporary dye which is 1-2 washes. It depends on what type marker you use
I have heard somewhere that it lasts about 2 weeks, but I haven't found a place to prove it.
It depends on the dye you used: if it was temporary when you shampoo your hair the dye will wash out straight away. If it is semi permanent it was last 6-8 washes, if it is a quasi permanent you get 12-24 washes and if it is permanent it won't fade. So depending on how long your dye will last you can wash your hair when you like.
team policing
Semi permenant hair dye lasts up to 24 washes/shampoos :}
You can use it as long as it hasn't been opened9the bottle not the box itself). The stores leave the boxes on the shelf for a long time.
raw hair dye.