What is a smoothing treatment?
A smoothing treatment is a hair treatment designed to reduce frizz, temporarily or more permanently smooth the hair shaft, and enhance the hair’s shine.
There are several types: keratin treatments (semi-permanent), so-called “Brazilian” straightening treatments, Japanese straightening treatments (permanent, involving a change in the hair’s structure), and chemical straightening.
These treatments differ in their composition, intensity, duration, and level of health risk.
These treatments are not harmless: they may contain powerful chemical active ingredients whose use is regulated by European Regulation (EC) No. 1223/2009 on cosmetics. Caution is advised.
What are the benefits of smoothing treatments?
Smoothing treatments offer several sought-after cosmetic benefits:
- Reduced frizz: particularly useful in humid climates.
- Easier styling: reduced styling time, more manageable hair.
- Long-lasting shine: a shinier, more polished appearance.
- Variable longevity: from a few weeks to several months, depending on the treatment.
These cosmetic benefits must be weighed against health risks and maintenance requirements (see the “Precautions” section).
What types of straightening treatments are available?
Several types of straightening treatments are available on the market:
- Keratin treatment: keratin proteins to temporarily tame the hair shaft. Typically lasts 3 to 6 months.
- So-called “Brazilian” straightening: typically combines keratin with straightening agents. Caution is essential: many formulas contain formaldehyde or **precursors (glyoxylate) that release formaldehyde when heated** (reaction with the straightening iron). See precautions below.
- Japanese straightening: a permanent treatment that alters the structure of the hair shaft (breaking disulfide bonds); results last until the hair grows out.
- Chemical straightening: strong products (hydroxides, thioglycolates), generally used on very curly or frizzy hair.
Is the straightening treatment safe for all hair types?
Smoothing treatments are not suitable for all hair types:
- Severely damaged, brittle, or weakenedhair: risk of increased breakage; should be avoided or postponed until the hair has been restored.
- Hair that has already been chemically treated (multiple colorings, bleaching): risk of cumulative weakening.
- Irritated scalp, seborrheic dermatitis, psoriasis, eczema: should be avoided until the condition has resolved.
- Known contact allergies to thioglycolates, formaldehyde, or preservatives.
Pregnant and breastfeeding women: as a precaution, avoid any chemical hair treatments during these periods; consult your doctor or midwife.
A preliminary consultation with a qualified professional is essential to assess tolerance and the suitability of the treatment.
How does a hair-smoothing treatment work?
A salon-based smoothing treatment generally involves several steps:
- Wash the hair with a clarifying shampoo to remove impurities.
- Application of the product strand by strand, in an amount appropriate for the length and type of hair.
- Drying and straightening with a flat iron (heat setting 180–230 °C depending on the product) to seal in the treatment.
- Rinsing and styling according to the client’s preferences (this step may vary depending on the type of treatment).
The salon must have adequate ventilation, and staff must wear appropriate protective equipment when using products that emit irritating fumes (formaldehyde, glyoxylate).
How long does a straightening treatment last?
The duration of a straightening treatment depends on the type of treatment and the maintenance routine:
- Keratin treatment: 3 to 6 months, dependingon the productsused and maintenance.
- Brazilian straightening: 3 to 5 months on average.
- Japanese straightening: permanent, until the hair grows out naturally.
- Chemical straightening: Permanent on the lengths; regrowth must be treated regularly.
Using unsuitable products (harsh sulfates, chlorine, salt) or excessive heat can significantly shorten the duration of the results.
What are the possible side effects of straightening treatments?
The adverse effects of straightening treatments can be significant:
- Scalp irritation and burns: particularly with Japanese straightening (hydroxides) and chemical relaxers.
- Hair breakage: weakened hair, split ends, loss of length.
- Hair loss in cases of cumulative weakening or improper application.
- Contact dermatitis, allergies: to thioglycolates, ammonia, formaldehyde, and their derivatives.
- Acute respiratory irritation and asthma: a major risk in case of exposure to formaldehyde or its precursors (both clients and hairstylists).
- Documentedlong-term carcinogenic risk for formaldehyde (see Precautions section).
Any severe reaction (shortness of breath, respiratory tract irritation, burning sensation, intense itching, red patches) requires immediate cessation of the treatment and a medical consultation.
How should you care for your hair after a straightening treatment?
To maintain the effects of a straightening treatment and preserve hair health:
- Shampoos without harsh sulfates: strong sulfates accelerate the breakdown of the treatment.
- Avoid seawater and swimming pools: salt and chlorine weaken the hair and reduce the longevity of the straightening treatment.
- Limit heat from styling tools (hair dryers, flat irons, curling irons).
- Regular hydration: conditioners, nourishing masks, and plant-based oils.
- Useanti-frizz serums and heat protectants before blow-drying.
- Get your ends trimmed regularly to minimize breakage.
How much does a straightening treatment cost?
The cost of a straightening treatment at a salon varies depending on several factors: type of treatment, hair length and thickness, the salon’s reputation, and the region.
Approximate prices in France generally range from €150 to €600, or even more for Japanese treatments on long hair.
Before any treatment, ask for a detailed estimate and the full list of ingredients in the product being used; a qualified professional will be able to provide this information.
Can you perform a hair-smoothing treatment at home?
At-home hair-smoothing kits are available on the market, but their use comes with several limitations and risks:
- Increased risk of errors: incorrect dosage, processing time, or application.
- Risk of scalpburns, hair breakage, and hair weakening.
- Insufficient ventilation: Irritating fumes (formaldehyde and derivatives) are not properly ventilated in a home setting.
- No prior assessment: it is impossible to evaluate the actual condition of the hair shaft and scalp.
- Composition is sometimes unclear: products from outside the EU may contain concentrations that do not comply with Regulation (EC) No. 1223/2009.
For powerful chemical treatments, it is clearly preferable to have a trained professional perform the procedure. Gentle treatments (masks, oils, anti-frizz serums), on the other hand, can be used safely at home.
Should you use a smoothing treatment on colored or chemically treated hair?
Using a smoothing treatment on colored or chemically treated hair requires special precautions:
- Risk of cumulative damage: coloring + bleaching + straightening = multiple stresses on the hair shaft.
- Possible color changes (lightening or shift in shade) with certain treatments.
- Minimum time between coloring and straightening: generally 2 to 4 weeks, depending on the treatment.
- Test on a hidden strand to assess compatibility before proceeding with the full treatment.
Be sure to consult a qualified professional before combining treatments.
What is the difference between a smoothing treatment and a chemical straightening treatment?
Smoothing treatments and chemical straightening differ in their mechanism and duration:
- Keratin smoothing treatment: temporary effect; does not alter the internal structure of the hair fiber. Lasts 3 to 6 months.
- Japanese straightening: permanent; involves the chemical breakdown of keratin’s disulfide bonds, lasting until the hair grows out.
- Chemical straightening: permanent; uses sodium hydroxide, guanidine hydroxide, or ammonium thioglycolate. Suitable for very curly or kinky hair.
Permanent treatments are more drastic and carry greater risks; they require professional expertise and careful attention to the ingredients.
Are there natural alternatives to chemical straightening treatments?
Several gentler alternatives exist that do not alter the hair’s structure:
- Vegetable oil masks: argan oil, olive oil, jojoba oil, castor oil—these moisturize and tame the hair shaft.
- Rinsing with diluted apple cider vinegar (1 tablespoon per 1 L of water): closes the hair cuticle and adds shine. Avoid using on damaged or very sensitive scalps.
- Homemade nourishing masks (avocado, mashed banana, honey): provide additional nourishment; use fresh.
- Cosmetic anti-frizz serums made with lightweight silicones or plant-based oils.
- Careful blow-drying with a suitable brush and heat protectant.
The results are less dramatic and less long-lasting than chemical treatments, but they preserve the hair’s integrity.
What are the signs that indicate a hair-smoothing treatment is necessary?
Several signs may indicate a need to consider a smoothing treatment:
- Pronounced and persistent frizz despite the use of anti-frizz products.
- Hair that’s unruly on a daily basis and difficult to style.
- Lack of shine and a dull appearance.
- Very long styling times and a recurring need for intense blow-drying.
Before undergoing any chemical treatment: first try gentle alternatives (masks, oils, anti-frizz serums) that may be enough to significantly improve the look of your hair without the associated risks.
What is the ideal frequency for a straightening treatment?
The frequency of a straightening treatment depends on the type of treatment and the condition of your hair:
- Keratin treatment: every 3 to 6 months, depending on regrowth and longevity.
- Brazilian straightening: generally every 3 to 5 months, without excessive buildup.
- Japanese straightening: root touch-ups every 6 to 12 months (the lengths remain treated).
- Hair straightening: root touch-ups every 2 to 3 months.
Excessive accumulation of chemical treatments permanently weakens the hair shaft. Space out treatments and support maintenance with nourishing products between salon visits.
Consult a qualified professional for personalized recommendations based on the actual condition of your hair.
