September 9th 2012 14:02
Just keep in mind that if you don't bleach your hair, you may notice that blue dye will turn green quickly.
Once you've bleached your hair, wash and condition your hair. If you hair is yellow after bleaching, you may want to tone it, as well.
Dry your hair thoroughly.
Now, follow the directions on the package. Don't use vaseline on your scalp, as it may get on your hair, which will result in hair that isn't blue or is oily. It's better to just wear old clothes and use medical tape around your scalp. You can use a washcloth to wash off the blue dye that gets on your skin.
The general rule with dying your hair "odd" colors, is that the longer the dye sits, the better the color will set. Some claim that sleeping with the dye in won't hurt your hair.
The dye will set in wet or dry hair, but if you blow dry your hair, the dye will penetrate into the hair shaft, and it will be more intense and will stay longer. So, you may want to use a hair dryer for about 15 minutes once every hour.
When you're ready to remove the dye, you want to seal it first. Use vinegar to seal in the color. Then, rinse out the dye with cold water.