30 volume 9 developer.
Hair color developer 20 vs 30.
20 volume developer 20v 6 peroxide is the most commonly used.
First off it is optimal for covering grey hair.
For light colored hair such as light brown to a normal dark brown you can use a 20.
You could upgrade to volume 30 to change your color 3 to 4 shades but keep in mind it can damage thin or fine hair.
For slightly bigger changes in hair color opt for volume 20 developer which will change your color by 1 to 2 shades.
Also you d use it to stay anywhere around the level your hair already is or to lift 1 2 levels.
Benefits of hair developer.
The 30 volume developer also works like 20 volume but it will lighten the hair s original color by two to three and is more efficient when the desired color is no more than two levels lighter than the original color.
Without the developer you would never achieve a significant changes in the color of your hair.
The hair color and the developer are mixed in a certain ratio to form a tint mixture which is then applied to the hair.
Activation hair.
Works similarly to a volume 20 developer except it lifts a hair starting color by 2 3 levels and works best when a desired color is not more than 2 levels lighter than the existing hair shade.
Choose a 30 volume developer when you want a developer that is stronger for a lighter and deeper color.