The difference can be understood by asking how deeply the colour sits in the hair and what happens to it over time.
A useful way to picture a strand of hair is as a pipe with layers. The cuticle forms the outside, the cortex lies farther inside, and the medulla is the innermost part. This simple model helps explain why some colours wash away quickly while others remain in the coloured portion of the hair.
Temporary colour: colour on the outside
Temporary colour remains mainly on the outer part of the hair.
Think of it like putting paint on the surface. The colour is visible, but washing removes it. A temporary colour therefore does not have the same lasting behaviour as a dye that penetrates farther into the strand.
Semi-permanent colour: colour that penetrates farther but fades
Semi-permanent colour penetrates from the cuticle into the cortex.
The cuticle is repeatedly affected as the hair is washed and shampooed, so the colour gradually fades. This is why a semi-permanent result can look good initially but progressively lose intensity.
The natural henna-and-indigo system discussed here is treated overall as semi-permanent because the darker colour effect associated with indigo fades, even though henna itself holds for much longer.
Permanent colour: colour that remains in the coloured strand
Permanent colour is described as penetrating more deeply into the hair. Once the existing strand has been permanently coloured, the colour remains in that portion of the hair.
This does not mean that a person will never see grey again.
Hair continues to grow from the scalp. If the new growth is grey or white, that new hair has never been coloured. A visible pale line at the roots can therefore appear even while the previously coloured length remains dark.
Why this distinction changes how you judge colour performance
Suppose someone says, “My grey came back after a few weeks.”
That statement alone does not tell you whether the permanent colour faded. Look at where the grey is appearing.
If previously coloured lengths have lost their colour, that is fading. If the coloured length remains dark but new white hair is appearing from the scalp, that is new growth.
Permanent colouring therefore becomes primarily a matter of touching up new roots rather than repeatedly colouring the entire hair length. Repeatedly exposing the full length to chemical colouring can make the hair dry, brittle and frizzy. The most useful question is not simply, “How long before I see grey again?” It is: “Did the colour leave the hair I already coloured, or has new uncoloured hair grown?” That distinction tells you far more about whether the colour actually lasted.
Related Herbal Hair Dye Guides
- Why Do Grey Roots Reappear After Permanent Hair Colour?
- Is Herbal Hair Dye the Same as 100% Natural Hair Dye?
- Can Herbal Hair Dye Make Black Hair Brown or Burgundy?
Main guide: Herbal Hair Dye Explained: Natural Colour, Grey Coverage, Ingredients and Common Problems
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