Plant-based hair dye after a Brazilian blowout or keratin treatment

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Brazilian blowout: what it really does to your hair

The Brazilian blowout — also known as Brazilian keratin treatment — is a hair treatment that smooths and tames curly, wavy or unruly hair for 2 to 5 months. Unlike a permanent relaxer, it is not irreversible: it gradually fades with washing.

Its mechanism of action is important to understand when it comes to colouring:

  • A solution based on hydrolysed keratin (and often formaldehyde or its alternatives — glyoxylic acid, glutaraldehyde) is applied to the hair
  • The intense heat of the flat iron (230–240°C) chemically seals the keratin into the cuticle and the inner cortex
  • This "sealing" of the cuticle is precisely what causes the problem for dye applied afterwards

Why colouring is more difficult after a blowout

The hair cuticle is the outer protective layer of the hair shaft, made up of overlapping microscopic scales. Colouring agents — whether plant-based or chemical — penetrate the hair through this cuticle.

After a Brazilian blowout:

  • The cuticle is "sealed" by the polymerised keratin and heat. The scales are flattened and closed more tightly than usual
  • Pigments have a much harder time penetrating: colour may be less intense and less even
  • Colour longevity may be reduced: poorly fixed pigments rinse out more quickly
  • Tones may differ from what you normally achieve on untreated hair

The waiting period: why at least 4 to 6 weeks

Over time and with washing, the blowout gradually fades. The sealed cuticles begin to "open up" naturally, regaining a more normal permeability.

  • 4 weeks minimum for most standard Brazilian blowouts
  • 6 weeks minimum for the most intensive treatments (high-concentration keratin, glyoxylic acid formulas)
  • 2 weeks minimum for mild or express blowouts

The longer you wait, the more even and longer-lasting the colour will be. If you have the choice, 8 weeks after the blowout yields the best results.

The ideal order if you want both treatments

The golden rule among professional hairdressers is clear:

  1. Always colour before straightening: plant-based colour should be applied first. The Brazilian blowout applied afterwards closes the cuticle and may even improve the retention of plant pigments already in place.
  2. If you have already had a blowout: wait 4 to 6 weeks, test on a strand, then colour.
  3. Never do both on the same day: combining treatments in one session significantly weakens the hair shaft.

What to expect on blowout hair — realistic results

If you colour after the recommended waiting period, here is what you can reasonably expect:

  • Brighter, more translucent colour: the smoothed cuticle reflects light differently. Colour may appear shinier but less intense in depth.
  • Slight reduction in longevity: expect 4 to 5 weeks of colour retention instead of 6 to 8 on untreated hair.
  • Variable evenness: the most treated areas may absorb colour less readily than natural regrowth.

The two-step application: the technique to maximise colour uptake

To optimise colour on blowout hair, a two-step application is strongly recommended:

  1. First application: 45 minutes to 1 hour, rinsed as normal
  2. Intermediate drying: leave to dry for 24 to 48 hours
  3. Second application: an additional 30 to 45 minutes

This technique allows pigments to build up in successive layers, compensating for the reduced permeability of the smoothed cuticle. The result is noticeably more intense and even than a single extended application.

The strand test: essential

Before colouring your entire hair after a blowout, a strand test is strongly recommended:

  1. Take a small strand from a less visible area (nape of the neck)
  2. Apply the prepared paste as normal
  3. Rinse after 45 minutes
  4. Assess the colour achieved on the dry strand

If the uptake is insufficient, increase the processing time or opt for the two-step technique. If the uptake is good, proceed with the full application with confidence.

Maintaining colour on blowout hair

On hair that has undergone a Brazilian blowout, a few habits will prolong plant-based colour retention:

  • Sulphate-free shampoos (sulphates accelerate the fading of both the blowout and the colour)
  • Cool water for the final rinse rather than hot water
  • Avoid prolonged baths and swimming pools (chlorine)
  • A post-shampoo argan oil or shea butter treatment nourishes the fibre and can slightly extend pigment retention

Frequently asked questions

Will plant-based hair colour fade my blowout?
No. Plant-based powders have no effect on the polymerised keratin of the blowout. They neither accelerate nor extend its natural fading.

Can I have a blowout on hair already coloured with plant-based dye?
Yes. A Brazilian blowout applied to hair already coloured with plant-based dye presents no particular problem. Some hairdressers even find that the blowout further "seals" the plant-based pigments already in place by closing the cuticle over them.

Does plant-based colour last less long on blowout hair?
Slightly, yes — especially in the first few weeks after the blowout. After 6 to 8 weeks, the difference diminishes as the blowout fades.

Our recommendation

The practical rule to remember: wait at least 4 to 6 weeks after your blowout, do a strand test, and use the two-step technique to maximise plant pigment uptake. If you are planning both treatments in advance, always start with the plant-based colour first, then the blowout a few weeks later. Your hair will thank you for it.

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