What is the purpose of a developer in hair color applications?

The purpose of a developer in hair color applications is to activate the dye and help it penetrate the hair shaft. Developers contain hydrogen peroxide, which is crucial for initiating the chemical reaction necessary for the hair color to work effectively. When mixed with hair dye, the developer opens the cuticle layer of the hair, allowing the color molecules to enter and bond with the hair structure. This penetration is essential for achieving the desired color result, as without the developer, the dye would not be able to effectively alter the hair's pigment. The use of a developer also plays a critical role in determining the level of lift – or lightening – achieved during the coloring process, therefore impacting the final outcome of the hair color application.