In hairdressing, what is the purpose of a filler?

A filler serves a specific purpose in hairdressing, particularly in color application and correction. Its primary role is to provide an even base for subsequent color treatments. Fillers are typically used when hair has been previously colored or has varying porosity levels. By filling in the gaps in the hair structure, they help ensure that color absorbs evenly across all areas of the hair, promoting uniformity in the final result.

Using a filler can help achieve better color retention and vibrancy, preventing issues such as patchiness or uneven tones. This is especially important when transitioning between colors, such as going from a darker shade to a lighter one, as it helps to create a smooth canvas for the new color application.