The question comes up in almost every smoothing consultation: "My hair is already coloured (or bleached, or a bit over-processed) — will a keratin treatment make it worse?" It's a fair worry. Keratin treatments involve heat, chemistry, and a flat iron run at temperatures most colour-treated hair never sees outside a salon. Done properly, on the right hair, at the right time, it's one of the safest ways to cut frizz and blow-dry time in half. Done on the wrong hair, at the wrong time, it can push already-compromised strands past what they can handle. Here's the honest breakdown.
Is a keratin treatment actually safe for damaged or colour-treated hair?
Yes, in most cases — but it depends on the hair's structural condition, not simply whether it's been coloured. The deciding factor is elasticity and cuticle integrity, not colour history. Colour-treated hair that still stretches and springs back when wet, with an even, unbroken cuticle, takes a smoothing treatment well. Hair that's already fragile from repeated bleaching, over-processing, or heat damage is the hair that struggles, because a keratin treatment adds another round of heat on top of chemistry the hair has already absorbed.
In consultation, we test porosity and elasticity before anything goes near the hair. If a strand snaps rather than stretches when wet, or if colour has left the cuticle raised and porous, we'll either recommend a bond-building treatment first or hold off on keratin altogether until the hair has recovered. That's not us being cautious for the sake of it — it's the difference between hair that comes out smooth and glossy, and hair that comes out smooth for two weeks then starts breaking at the ends.
What actually happens to hair during a keratin treatment?
A keratin solution is applied to clean, dry hair, then dried and sealed in with a flat iron at 180–230°C, run over small sections multiple times. That heat is what locks the smoothing effect in — and it's also the step that requires the most judgement on already-compromised hair. The keratin itself isn't the risky part; keratin is a protein your hair is already made of, and formulas without formaldehyde (which is what we use) don't carry the same fume and bond-damage risk that gave keratin treatments a bad reputation a decade ago.
The real variable is heat tolerance. Virgin or healthy colour-treated hair can take repeated passes at 200°C+ without issue. Hair that's already lost internal bonds from bleach, or that's been over-toned or double-processed recently, has less structural reserve to absorb that heat safely. This is why timing and sequencing with colour matters more than most people expect.
How long does a keratin treatment actually last, and why does frizz creep back?
Our professional keratin treatments hold for 10–16 weeks, with frizz control fading gradually rather than dropping off a cliff. The single biggest factor in how long it lasts is wash frequency and product choice, not the treatment itself. Washing more than 2–3 times a week, using sulfate shampoo, or swimming in chlorinated or salt water without protection strips the smoothing film faster — we see clients in Perth lose weeks of results over summer from pool and beach exposure alone.
Should keratin come before or after a colour appointment?
Colour first, keratin second, with at least a two-week gap between them. Keratin treatments seal the cuticle, which slows down how evenly colour can process afterwards — so colouring into already-smoothed hair often gives patchier, less predictable results. Doing it the other way around, colour then keratin, means the smoothing treatment finishes the job by sealing in the colour's shine and calming any post-colour frizz.
If you need both and you're tight on time, tell your stylist that upfront in consultation. We'll sequence it properly rather than trying to compress both processes into one appointment, because rushing this order is exactly how people end up with uneven colour and a treatment that doesn't hold. If colour correction is part of the picture, it's worth reading how we approach staged colour correction and consultations before booking either service.
How do you look after keratin-treated hair at home?
Keep washing to 2–3 times a week, use sulfate-free products, and avoid tight hair ties or clips for the first three days. Everything after that first 72-hour window is about slowing down the natural fade, not preventing it entirely — keratin treatments are semi-permanent by design and will grow out and wash out over time regardless of how careful you are.
Beyond a sulfate-free shampoo and conditioner, a leave-in or lightweight oil helps on humid Perth days without weighing hair down — Infuse My.Colour Cellular hydrate range best suited to smoothed hair that need slip without grease. If you swim regularly, rinse and apply a leave-in conditioner before getting in the pool or ocean; wet hair with a barrier absorbs less chlorine and salt than dry hair does.
Frequently asked questions
Can you colour your hair after a keratin treatment?
Yes, but wait at least two weeks and expect processing to take slightly longer, since the sealed cuticle is less porous. A patch and strand test is worth doing if it's been a while since your last colour.
Will a keratin treatment make fine hair go flat?
It can, if applied root-to-tip on fine, low-density hair. We typically keep keratin off the root area on finer hair types and focus it mid-shaft to ends, which controls frizz without collapsing volume.
Is keratin the same as a Brazilian blowout?
No. Both use heat to seal a protein-based solution into the hair, but formulations, processing time, and the amount of straightening versus frizz-reduction differ between brands and techniques — ask your stylist which formula suits your hair goal specifically.
How soon can you wash your hair after treatment?
Immediately after service but why would you ...
Bureau The Salon — 444 Beaufort St, Highgate, Perth. Book your consultation via Fresha. See more transformations on Instagram.
