The formulation of permanent dyes is complex, and manufacturers go to great lengths to attain long-lasting colour that does minimal damage to the strength and elasticity of your strands. They work by penetrating your hair’s cuticle (protective outer layer), and therefore risk causing moisture loss from your strands
Because permanent dyes cannot be washed out, you may want to trial a new colour by using a semi-permanent or temporary dye first. (However, this will not be possible if you are going lighter, since lightening dyes always contain permanent bleaching agents.)
Advantages of Permanent Dyes
- Permanent dyes do not have to be applied as often as semi-permanent (temporary) colours.
- There is a wider range of permanent colour shades.
- They are often more natural-looking than temporary dyes.
- They provide full coverage of grey hairs.
- Because they do not wash out, permanent dyes encourage regular shampooing, which supports healthy hair.
Disadvantages of Permanent Dyes
- Can be more damaging to your hair than semi-permanent or temporary dyes.
- The chemicals used are stronger.
- The mixture usually has to be left on for a longer period of time.
- Cannot be washed out if you are unhappy with the colour.
- Are more likely to cause allergic reactions, ranging from mild to severe.