Wisconsin Barber Practice Exam

Hydrogen peroxide is commonly used as a developer in hair dyes, helping to activate the aniline derivative tint and penetrate the hair shaft. Option A, neutralizer, is used to stabilize the coloring process and close the cuticle after dyeing. It is typically used after the developer. Option B, cortexer, is not a common term in hair coloring and there is no known usage of it in relation to hydrogen peroxide or aniline derivative tint. Option C, fixative, is used to hold the dye molecules in place and prevent them from fading. It is usually used in conjunction with a developer and neutralizer, but is not the main component of the dyeing process. Therefore, the correct answer is D developer.