What characteristic typically distinguishes permanent colour from other types of dye?

Permanent hair color is distinguished by its ability to provide long-lasting results. This type of dye penetrates the hair shaft and chemically alters the hair structure, which allows for a more durable and effective change in color compared to semi-permanent or temporary dyes. While the latter types often coat the hair rather than change it at a molecular level, permanent color creates a lasting effect that does not wash out after a few shampoos.

The longevity of permanent color means that it can successfully cover gray hair, making it a popular choice for those looking to maintain their desired color over an extended period. This allows for fewer touch-ups and longer intervals between applications, making it a practical option for clients seeking consistent, vibrant color for their hair.