Keratin treatment vs. Japanese hair straightening.

Both treatments use heat and a flat iron, and both tame frizz. A keratin smoothing treatment coats and protects the hair, then washes out gradually over a few months. Japanese hair straightening permanently changes the hair's structure. Here's how to choose.

10–12 wksKeratin smoothing, washing out gradually

PermanentJapanese straightening, on treated hair

1.5–3 hrsKeratin, in the chair

3–5 hrsJapanese, in the chair

Benefits & drawbacks

Keratin treatment pros and cons.

Keratin smoothing

Keratin treatment

Softer, frizz-free finishSmooths and adds shine while keeping some body and natural movement.
Shorter appointmentUsually about 1.5–3 hours in the chair.
No regrowth lineIt washes out gradually and evenly, so there's no sharp line between treated hair and new growth.
Flexible stylingYou can still curl it or add volume with a round brush.
Works on most colored hairSuitable for highlighted, colored and lightened hair, and it enhances color and shine.
CumulativeEach treatment builds on the last, so you can go longer between appointments.

Not permanentResults typically last 10–12 weeks, so it needs repeating a few times a year.
Smooths more than it straightensIt relaxes roughly 50–90% of curl. Very curly hair won't come out fully straight.
Aftercare mattersA sulfate-free shampoo is essential, and you'll wait two days before your first wash.

Thermal reconditioning

Japanese hair straightening

Permanent on treated hairThe new shape doesn't wash out; only new growth needs a retouch.
Truly straightBreaks up wave, curl and stubborn frizz that keratin can only soften.
Fewer appointmentsRetouch new growth roughly every 6–12 months.

Long appointmentAbout 3–5 hours, and it is unforgiving of mistakes.
Less flexibleHair stays straight; curls only hold with heat styling.
Not for all hairHeavily bleached or lightened hair may not qualify.

Side by side

Keratin vs. Japanese straightening, point by point.

	Keratin treatment	Japanese hair straightening
How it works	A keratin smoothing formula is sealed onto the hair with a flat iron, creating a protein layer over the cuticle. The hair's inner structure isn't changed.	A thio-based solution opens the bonds that hold curl, the hair is flat-ironed straight, then a neutralizer locks the new shape in.
Result	Smoother, shinier, less frizzy. Wave is softened; wavy hair usually dries straight.	Straight, from sleek to straight with natural movement.
How long it lasts	About 10–12 weeks, washing out gradually.	Permanent on treated hair. Retouch new growth every 6–12 months.
Time in the chair	About 1.5–3 hours.	About 3–5 hours.
Price	From $360.	Priced at consultation.
Best for	Frizzy, wavy or damaged hair you want smoother and faster to style.	Wavy, curly, frizzy or coarse hair you want straight.
Colored or lightened hair	Generally suitable, including platinum blonde with adjusted iron heat.	Often possible after a strand test. Heavily bleached hair may not qualify.
Curling afterward	Curls hold normally.	Possible with heat.
First days after	Wait two days before washing.	No washing or tying back for about 72 hours.

Timing varies with your hair's length, density and history. Your specialist will confirm at consultation.

Types of keratin treatments

Types of keratin smoothing treatments.

Not every keratin treatment is the same.

"Keratin treatment", "Brazilian Blowout", "keratin straightening" and "BKT" are often used interchangeably, but the formulas behind them differ in strength, longevity and chemistry.

Often called a Brazilian keratin treatment or BKT

Classic keratin smoothing

The original long-lasting smoothing treatment. A keratin formula is applied section by section and sealed into the cuticle with a flat iron, giving the strongest smoothing and the longest-lasting results.

Finish: Strongest smoothing; wavy hair often dries straight
Lasts: About 10–12 weeks
Good for: Thick, frizzy or very wavy hair

A brand name, often used for any keratin treatment

Brazilian Blowout

Brazilian Blowout is a specific professional brand of smoothing treatment. The name is used so widely that many people say "Brazilian Blowout" when they mean any keratin smoothing treatment.

Finish: Smooth, shiny, keeps some body
Lasts: Up to about 12 weeks
Good for: Frizz and shine without going flat

When you book, choose Keratin Treatment for any smoothing treatment; your specialist will choose the right formula for your hair at your appointment. For permanent straightening, choose Japanese Hair Straightening.