What is the difference between permanent, semi-permanent and demi-permanent hair colorants?
The basic difference is durability i.e. resistance of the dye to multiple shampooing and environmental conditions. Semi-permanent colorants last typically for few days and up to 5 shampoos. Demi- permanent colorants last anywhere from 10 to15 days and up to 15 shampoos. Permanent colorants should last at least three weeks and up to 20 shampoos. It is a common mistake to assume that a permanent dye must be an oxidative dye. An oxidative dye must have developer that contains Hydrogen Peroxide. However non-oxidative dyes (i.e. dyes without a developer) that are typically called semi-permanent can also impart a permanent color.
