* Hair's Natural Pigment: Natural hair color comes from melanin pigments. Blonde hair has very little melanin, meaning it's light enough for other colors to show up easily.
* Dye's Pigments: Hair dye contains artificial pigments. Violet dye has pigments that absorb most colors of light except for violet, which is reflected back to our eyes, making us perceive the hair as violet.
* Dyeing Process: The dye molecules penetrate the hair shaft (either by temporarily coating the outside or by chemically altering the hair to allow the dye to enter). The violet pigments then remain in the hair, coloring it.
Why specifically violet?
Because the dye is specifically formulated to contain violet pigment. The exact shade of violet you get depends on the specific dye used, its concentration, and the underlying color of the hair. If the hair has yellow tones, the violet might neutralize some of the yellow, resulting in a cooler, more ashy violet.
In summary, the violet color in dyed blonde hair is simply due to the presence of violet pigment molecules in the hair that reflect violet light.