depending on how many tones away you want to get from the color you have now. If you are going lighter you will want to use a 20 (30 is fine too if you are trying to go over 3 tones but be careful as it will dry your hair out more) otherwise if going darker you'll want to use a 10
Cream developer alone will not lighten your black hair. You will need to use a bleach or lightener with the cream developer to lighten it.
yes.
Yes a 40 developer will lift your hair color 4 times. It will lighten your hair. You will need to mix it with a color and follow the directions on the box or packaging.
Yes, bleach or a high lift color mixed with 30 vol. developer is needed in order to lighten hair.
No. It is not recommended to use hair dye without the developer or without it's original content. However if you were to use a temporary rinse then a developer isn't needed. If you are using any dyes that are not already ready to go (previously mixed by the manufacturer) then you will need to follow those instructions and mix your developer with the color.
you can but it will make your hair extremely orange or brassy. It would be better for you to use bleach with the 20 volume developer..20 volume does the least amount of damage to your hair..just be sure to build the strength of your hair back up with conditioning treatments.
Yes, a 50V developer can be used to lighten hair but more than likely it will break the hair and cause irreversible damage. A 30V is recommended instead.
It will remove the pigment from your hair and lift your hair color 3 times (lighten it).
It most likely will not work you will need developer to make the bleach activate and do what it needs todo which is lighten your hair. If you use water it will not activate or help lift the bleach.
The easiest way to lighten your hair is to use bleach designed for hair.
10
Yes, this will work, but I recommend using 20 volume developer instead of 30 volume and watch the hair closely.