Keratin, Brazilian or Japanese straightening: differences and which to choose
Comparing keratin (Keratin Infusion), Brazilian and Japanese straightening: composition, duration, formaldehyde rules and which hair type each suits.
If you have been thinking about straightening your hair but get lost between so many names —keratin, Brazilian, Japanese, tanin, Keratin Infusion…—, this article is for you. They are three chemically different treatments, with very different durations, effects and aftercare. Choosing the right one is the difference between healthy hair and hair that looks damaged for months.
What you will learn:
- The real difference between keratin, Brazilian and Japanese straightening (spoiler: they are not the same).
- How long each one lasts and which hair type it suits.
- How the new European formaldehyde regulation (EU Regulation 2022/1181) affects these treatments.
- Which straightening fits your hair type and whether you have bleached hair.
- The vocabulary confusion
- Keratin treatment (Keratin Infusion)
- Brazilian blowout
- Japanese straightening
- Comparison table
- Which one should I choose
The vocabulary confusion
The first problem is linguistic: in Spain, "keratin straightening" and "Brazilian straightening" are often used as synonyms, but technically the Brazilian is a type of keratin treatment originated in Brazil. Today, with the European regulation on formaldehyde, both terms refer in practice to the same type of temporary, non-invasive straightening.
The Japanese straightening, on the other hand, is something completely different: a permanent treatment that breaks the hair bonds and reshapes them.
Keratin treatment (Keratin Infusion)
It is a temporary, non-permanent treatment that coats and seals the hair fibre. At Milanocenter we mainly work with Keratin Infusion by GOA Organics, formulated with an Alpha Hydroxy Acid (AHA) complex that binds to the hair proteins and promotes their restructuring through acidity, in synergy with the natural keratin of the hair.
- Composition: AHA + hydrolysed keratin + amino acids. Formaldehyde-free.
- Effect: natural straight with movement, not flat-iron-like. Eliminates frizz and adds extreme shine.
- Duration: 4 to 6 months. The effect fades progressively with washes; no visible "root effect" as the hair grows.
- Time in salon: 2-3 hours depending on length.
- Compatibility: safe for coloured, bleached, highlighted or sensitised hair.
- Aftercare: being formaldehyde-free, there is no need to wait 72 hours to wash; hair can be wet and tied up from day one.
It is the main treatment in our straightening service, always with a prior assessment of the fibre.
Brazilian blowout
The classic Brazilian blowout became popular in the 2000s with formulas based on keratin + formaldehyde (or formaldehyde-releasers such as methylene glycol). Formaldehyde sealed the keratin to the hair through heat, offering a long-lasting straight. The problem: formaldehyde is classified as a human carcinogen by the IARC.
The regulatory change: goodbye to formaldehyde
The European Union has regulated formaldehyde in cosmetics through Regulation (EU) 2022/1181:
- Since 31 July 2024, products with a free formaldehyde concentration above 0.05% cannot be placed on the market.
- Since 31 July 2026, the marketing of cosmetics releasing formaldehyde is banned.
- Products releasing formaldehyde above 0.001% (10 ppm) must label it mandatorily.
Conclusion: in 2026, a Brazilian blowout applied in a professional salon in Spain should not contain formaldehyde. In practice, current legal "Brazilian" formulas are practically equivalent to a formaldehyde-free keratin treatment such as Keratin Infusion.
- Current composition: hydrolysed keratin + proteins (silk, collagen) + oils + amino acids. Formaldehyde-free.
- Effect: natural straight with some movement, similar to keratin.
- Duration: 3 to 5 months.
- Availability: this service is not offered at Milanocenter Estilismo: we work exclusively with Keratin Infusion (formaldehyde-free).
Warning: if you are offered a very cheap Brazilian blowout, with strong fumes, and you are asked not to wash your hair for 72 hours, it is a red flag: formaldehyde-based products above legal limits are likely being used.
Japanese straightening
Japanese straightening is a permanent and chemically aggressive treatment. Its active principle is ammonium thioglycolate, which breaks the disulphide bonds of the hair keratin. Once opened, the flat iron rearranges the structure and a neutraliser fixes the straight shape. From that moment on, the treated hair never curls again.
- Composition: ammonium thioglycolate + oxidising neutraliser.
- Effect: total, flat-iron straight, with no movement.
- Duration: permanent in the treated area. Requires root retouch every 6-9 months as the hair grows.
- Time in salon: 4-6 hours (the longest of the three).
- Compatibility: ideal for very thick, coarse, tightly curled hair. Not recommended on bleached hair, intense highlights or damaged hair: the risk of breakage is high.
- Availability: a permanent treatment we do not offer at Milanocenter Estilismo due to its aggressive and irreversible nature.
- Aftercare: 48-72 h without washing, no ponytails or hairpins, no water contact.
Comparison table
| Feature | Keratin Infusion | Brazilian (formaldehyde-free) | Japanese |
|---|---|---|---|
| Type | Temporary, sealing | Temporary, sealing | Permanent, chemical |
| Active principle | AHA + keratin | Keratin + proteins | Ammonium thioglycolate |
| Formaldehyde | No | No (since EU 2022/1181) | No |
| Effect | Natural straight with movement | Natural straight with movement | Flat-iron total straight |
| Duration | 4-6 months | 3-5 months | Permanent (root retouch 6-9 m) |
| Aggressiveness | Low | Low | High |
| Bleached hair | Yes | Yes | Not recommended |
| Time in salon | 2-3 h | 2-3 h | 4-6 h |
| Available at Milanocenter | Yes | No | No |
| Wait to wash | No | No (formaldehyde-free) | 48-72 h |
At Milanocenter Estilismo, straightening is quoted in a personalised consultation: length, density and hair condition determine the plan. Book your appointment and we will provide a fixed quote with no commitment.
Which one should I choose
- Fine, coloured or highlighted hair, I just want to remove frizz: Keratin Infusion.
- Wavy/curly hair, I want a natural straight without a permanent commitment: Keratin Infusion or formaldehyde-free Brazilian.
- Very curly, thick, virgin hair, I want a definitive straight: Japanese straightening (with prior assessment).
- Bleached hair or balayage: never Japanese straightening. Keratin Infusion is the safe option. Unsure about your colour? See our guide on highlights, dye or balayage.
- Looking for low maintenance and hair health: Keratin Infusion is the best result-health ratio. Complete it with our hair treatments.
"90% of those who ask us for 'Japanese straightening' actually want to get rid of frizz and manage their hair better, not a permanent flat-iron straight. After the assessment they almost always end up with Keratin Infusion, which is reversible and compatible with their colour." — The Milanocenter Estilismo team
Frequently asked questions
No. Keratin Infusion is a sealing treatment: it coats the cuticle without breaking the internal structure of the hair. In fact, the fibre is left more protected and nourished after the treatment. Real damage comes from excessive flat-iron use at home, not from the product.
Yes. It is recommended to wait 15-21 days between the keratin treatment and colouring to avoid interfering with the result. The ideal order is first colour or highlights and then keratin, as keratin seals and protects the pigment.
Between 4 and 6 months, progressively: the hair gradually returns to its natural texture, with no root effect or visible cut line. This is why it is ideal for those who do not want a permanent commitment.
In the European Union it should not. EU Regulation 2022/1181 limits free formaldehyde in cosmetics to 0.05% since July 2024 and bans its marketing from July 2026. If a salon offers a Brazilian with strong fumes and asks you not to wash your hair for 72 hours, be cautious.
No. By breaking the disulphide bonds of the hair, the effect is permanent in the treated area. The only way to remove it is to let the hair grow and cut the straightened part.
In most cases we recommend Keratin Infusion by GOA Organics: formaldehyde-free, compatible with colouring, 4-6 month duration and natural straight with movement. We carry out a prior hair assessment before choosing the treatment. Book online or call +34 966 090 360.
