When working with color pigments to color hair, the law of subtractive color mixing is something all should know. Subtractive color mixing means that light will be reduced when more color is added, creating darker colors.
The more color added or mixed the less light can be reflected, the darker the color gets, and the less luminosity it possesses.
When working with colored light, we use the law of additive color mixtures to also create lighter colors. Light colors can also be made visible through a filter.
red light + green = yellow
green + blue = cyan
blue + red = magenta
In the daily business in the salon, we do not talk about Magenta and Cyan, but about Red, Yellow and Blue.
Artificial light can’t always deliver true white light as it contains certain wavelengths. Different colored light may influence the perceived color of an object. The bluish light of a fluorescent lamp can cause light hair color to look ashy, while under the yellowish light of an electric bulb that same color seems more golden.
In the salon, this means a correct estimation of hair color should always be done under special daylight lamps or in the direct daylight as artificial light may cause misinterpretations. Different colored light causes hair to look different in the salon. When your client returns home, her light will also be different.
The first picture shows the hair color under blue light, the second picture under yellow and the last picture under red.
Learn more about Color Theory here.