What is a common cause of brassiness after coloring?

Brassiness after coloring is commonly caused by red or orange undertones becoming more visible when a lighter color is applied. This phenomenon occurs because when hair is lightened, the underlying pigments, which can be naturally occurring warm tones such as red or orange, may become more prominent. This is particularly common in darker hair that is lifted to a lighter shade. If the dye used does not effectively neutralize these warm tones, the result can be an unwanted brassy hue.

To prevent brassiness, colorists often use toners or dyes that have blue or violet pigments, as these colors are opposite red or orange on the color wheel and can help to neutralize the warmth. Understanding the underlying pigments of the hair and how they interact with color formulations is key to achieving the desired shade without brassiness.