Developer, also known as activator or even peroxide for short, is mixed with bleach or dye to lighten or color hair. It's a creamy product that contains hydrogen peroxide, and the amount of hydrogen peroxide is what determines developer volume.

What is the difference between developer and peroxide?

Peroxide is a thin, clear liquid and when you apply it to your hair, it thickens a little but still flows freely. Creme developer is consistently thick in structure. When you apply to the hair, it stays put, making it suitable for use in instances where you need only some parts of the hair bleached.

Can I use hydrogen peroxide instead of developer?

10 volume developer usually has 3% peroxide, whereas 20 volume developer has 6%. You can use either but the 20 volume developer will be much harsher on your hair. Hydrogen peroxide won't chemically burn your hair as bleach does, but it will dry it a lot. ... Peroxide lightens hair and it will damage your hair.