Which type of dye is known for building up on hair after continuous use?

Metallic dye is known for its tendency to build up on hair with continuous use. This type of dye contains metal salts that can create a layer of color on the hair, leading to a gradual increase in color intensity over time. Unlike other hair color types that may wash out or fade relatively quickly, metallic dyes can leave a residue that accumulates, particularly if used repeatedly without proper cleansing.

In comparison, permanent haircolor typically offers long-lasting results without significant build-up, as it works by penetrating the hair shaft and altering the hair's structure to create a new color. Demi-permanent haircolor usually lasts longer than semi-permanent options but does not usually build up in the same way that metallic dyes do, since it does not contain harsh chemicals to alter the hair structure permanently. Natural hair dyes may have fewer ingredients that would cause a build-up, focusing on plant-based components that offer a more temporary solution.