Should I bleach my hair before using it or does it look the same on brown hair?

Yes, you need to bleach dark hair first.

How long does it last?

As long as you are using a better quality, sulfate and paraben free shampoo, like ion’s, and u don’t shampoo daily, it lasts a few weeks but of course vibrancy lessens with each wash

Will it cover gray hair?

Hi, Thank you for contacting iroiro. Most of our colors should cover gray hair, however we can guarantee optimal result without lifting the original hair color. Have a super day!

How long does it last

That really depends. If you make sure to wash your hair with as cold of water as you can handle, use sulfate free shampoo AND CONDITIONER (yes conditioners can have sulfate in them) and also don't wash your hair like 3/4 times a week if you want the color to last SUPPER long. I personally use low sulfate shampoo and conditioner along with using lukewarm water for my hair and I don't think my hair is all that faded. And I dyed is in December. Even if it does fade. It's not to a bad color either. Just make sure you get the yellow out of your hair or it might turn green.