What is a common purpose of using fillers in hair coloring?

Using fillers in hair coloring is commonly aimed at achieving an even color application. When hair has been previously colored or has varying undertones, it can absorb new color unevenly. Fillers are designed to equalize the porosity of the hair, which helps ensure that the color adheres evenly throughout the strands. This process is particularly important when transitioning from a darker to a lighter shade or when applying a new color over previously colored or damaged hair.

The use of fillers can help prevent patchiness and achieve a uniform finish, as they create a more consistent canvas for the new hair color. This technique ultimately leads to a more professional and aesthetically pleasing result, making it a crucial step in the hair coloring process for colorists who want to achieve the best possible outcomes.