1. Ammonia-Free (Usually):
* Most quasi-hair colours are ammonia-free or have very low ammonia content compared to permanent dyes. Ammonia is a chemical that swells the hair cuticle, allowing permanent dyes to penetrate deeply. The lack of ammonia in quasi-colours means the cuticle remains largely intact.
2. Lower Hydrogen Peroxide (Developer) or No Developer:
* Quasi-colours typically use a lower volume of hydrogen peroxide (developer) than permanent dyes, or sometimes no developer at all. Hydrogen peroxide opens the hair cuticle and lightens the natural hair pigment.
* With lower volumes (or none), the developer mostly helps the colour adhere to the hair surface rather than causing significant lightening.
3. Colour Pigment Deposition:
* The colour molecules in quasi-dyes are designed to be larger than those in permanent dyes. These larger molecules can't penetrate the hair cuticle as easily.
* Instead, they coat the outer layer of the hair shaft, attaching themselves to the surface. This is why the colour fades over time with washing.
4. Fading:
* Because the colour pigments are not embedded deeply within the hair shaft, they are gradually washed away with each shampoo.
* The rate of fading depends on several factors, including:
* The colour itself: Some colours fade faster than others (reds and purples are notoriously quick to fade).
* Hair porosity: More porous hair may initially absorb more colour, but it can also lose colour more quickly.
* Washing frequency: The more you wash your hair, the faster the colour will fade.
* Shampoo type: Harsh shampoos strip away colour more quickly than gentle, sulfate-free options.
* Heat styling: Excessive heat can also contribute to colour fading.
Key Differences from Permanent Hair Dye:
| Feature | Quasi-Hair Colour (Demi/Semi-Permanent) | Permanent Hair Dye |
|-----------------|-----------------------------------------|----------------------------|
| Ammonia | Low or None | High (typically) |
| Developer | Low Volume or None | Higher Volume |
| Cuticle Opening | Minimal | Significant |
| Colour Depth | Deposits colour on the surface | Penetrates and alters colour|
| Longevity | Fades over time (6-28 washes) | Permanent (grows out) |
| Lightening | Minimal or None | Can significantly lighten |
| Damage | Less Damaging | More Damaging |
| Grey Coverage | Blends grey; doesn't fully cover | Usually complete coverage |
Benefits of Quasi-Hair Colour:
* Less Damaging: Due to the minimal cuticle disruption, quasi-colours are generally less damaging to the hair than permanent dyes.
* Gradual Fade: The gradual fading allows for a more natural transition as the colour washes out.
* Experimentation: Ideal for trying out new colours or enhancing your natural colour without a long-term commitment.
* Adds Shine: Can add shine and depth to the hair.
Limitations of Quasi-Hair Colour:
* Limited Lightening: Cannot lighten hair significantly. It can only deepen or match existing shades, or slightly alter the tone.
* Grey Coverage: Provides limited grey coverage; it's more likely to blend greys than completely cover them. Demi-permanent colours are slightly better at covering greys than semi-permanent because they use a low volume developer which helps with pigment penetration.
* Fading: The colour fades with each wash, requiring more frequent touch-ups.
* May not work on very dark hair: The colour might not be very visible on very dark hair, unless you are using a very deep or vibrant shade.
In summary, quasi-hair colours are a gentler alternative to permanent dyes that deposit colour on the surface of the hair, offering a temporary way to enhance or change your hair colour with less damage.