What is the oxidizing agent commonly used with demi-permanent and permanent colors?

The correct choice is developer, which is essential in the hair coloring process, particularly with demi-permanent and permanent hair colors. Developer contains hydrogen peroxide, which acts as the oxidizing agent. Its primary role is to open the hair cuticle layer, allowing the color molecules to penetrate the hair shaft for lasting color results.

When mixed with hair color, the developer helps to activate the color by providing the necessary oxygen needed for the chemical reaction that leads to the color change. For demi-permanent colors, typically a lower volume developer is used, while permanent colors often require a stronger volume to ensure proper lifting of the natural pigment.

While hydrogen peroxide is indeed a key component of the developer, identifying the developer as the oxidizing agent emphasizes its role in the overall formulation and application of hair color. This distinction is crucial for understanding how color products work and ensuring effective results in hair coloring techniques.