1. Hair dye substances – transform into dyes by oxidation
2. Direct hair dyes – dye directly, emphasize red-goldish and red shades
3. Alkalines – cause hair to swell, neutralise stabilizer acids and help peroxide to Penetrate. There pH is between 10-11.
4. Mediator substances – cause to attenuate or thicken
(O/Vsometimes gel)
