What is Keratin Smoothing? A 101 Guide to At-Home Hair Smoothing Treatments
28/11/2025
Everyday hair stressors like excessive heat styling, ongoing chemical treatments, UV damage, extreme weather, and aggressive brushing can all compromise the outermost layer of hair strands – the cuticle.
When cuticles are damaged, it means they’re lacking one essential protein: keratin. Fortunately, this is where an at-home keratin hair smoothing treatment can help.
This hair care solution to dull, frizzy strands has captured our attention, so we’re doing a deep dive on how keratin smoothing treatments work – both in and out of the salon.
Read on to find out how to get smooth, shiny hair using at-home hair smoothing treatments.
What is a keratin smoothing treatment?
A keratin smoothing treatment is a shine-enhancing, semi-permanent hair treatment that involves depositing a keratin-rich solution onto the hair shaft or cuticle, then sealing it with heat. Ideal for coarse, frizzy, dull, unmanageable strands, keratin smoothing treatments are traditionally performed in a salon by a professional – although there’s a range of temporary at-home solutions, too.
Keratin benefits for hair
Keratin is a natural protein found in hair (and nails), and it’s responsible for giving your strands strength, structure, and resilience. Keratin also plays an essential role in protecting your hair from everyday stressors that lead to damage and breakage.
When applied as a hair treatment, keratin deposits help ‘fill’ the gaps in the hair cuticle. This provides many benefits, such as:
- Reducing frizz
- Enhancing smoothness
- Softening strands
- Amplifying shine
- Preserving the vibrancy of colour-treated hair for longer
- Leaving strands less prone to tangling
- Making hair more resilient against breakage and easier to manage
How is a salon keratin treatment different from an at-home keratin smoothing treatment?
A salon keratin treatment is semi-permanent and uses professional-grade, highly concentrated keratin formulas to achieve a deep sealing effect on the hair.
Depending on the length and thickness of your hair, salon keratin treatments can take anywhere from two to four hours to apply. Salon keratin treatments are formulated with harsher ingredients and require high heat to seal the treatment – which can further damage and weaken already compromised hair.
On the other hand, at-home keratin smoothing treatments use a lower concentration of chemicals – and do not penetrate the internal structure of the hair. As a result, their effects are more temporary. As for application times, these will vary depending on the formula – but the end-to-end process is usually one to two hours at home.
The bottom line? At-home smoothing treatments, while less permanent, are much more cost-effective than salon keratin treatments – and they’re kinder to your strands, too.
How long does a keratin smoothing treatment last?
A professional salon keratin smoothing treatment typically lasts between three to six months. However, certain factors can impact longevity: such as your hair washing schedule, hair care formulas, heat styling habits, and exposure to chlorinated or salt water.
Enriched with a keratin smoothing complex and argan oil, the Garnier Fructis Keratin Sleek & Stay Hair Smoothing Serum provides up to 10 days* of smooth, shiny hair and results for up to five washes. Enabling you to enjoy salon-like smoothness and shine at home – without overprocessing.
*Instrumental test after application of the serum
Keratin treatment vs permanent straightening: what's the difference?
We’ve established that keratin treatments help smooth the surface of strands, but does a keratin treatment straighten hair?
You’d be forgiven for mistaking keratin treatments for permanent straightening. While salon keratin treatments can loosen natural curl patterns (a natural by-product of smoothing the hair cuticle), they don’t straighten hair textures.
Permanent straightening is a chemical process that penetrates the shaft to change the structure of hair texture – and requires new growth to return to its original texture. The risk of damage is much higher with chemical straightening, however, and the process can often lead to dryness and breakage.
How to do a keratin smoothing treatment at home
The Garnier Fructis Keratin Sleek & Stay Hair Smoothing Serum is simple to use at home – but it’s most effective when combined with our full Keratin Sleek System.
Below, we’ll guide you through our keratin hair care routine to help you boost shine, vitality, and manageability: from the initial wash to the final polished style.
- Wash your hair and scalp: Gently cleanse with the Garnier Fructis Keratin Sleek Anti-Frizz Shampoo to nourish dry, frizzy hair. Work the formula into a lather and rinse thoroughly.
- Condition your ends: After squeezing excess water from your strands, detangle and soften them with the Garnier Fructis Keratin Sleek Anti-Frizz Conditioner. Be sure to let the conditioner sit for two to three minutes before rinsing.
- Nourish deeply with a mask: For an extra dose of nourishment and frizz control, apply the Garnier Fructis Keratin Sleek Anti-Frizz Hair Mask from root to ends – avoiding the scalp. Leave on for three to five minutes, then rinse.
- Apply your at-home keratin smoothing treatment: Shake the Garnier Fructis Keratin Sleek & Stay Hair Smoothing Serum bottle to activate the formula, then dispense one pump onto damp hair. The serum coats the hair fibre with a waterproof and heat protecting film (up to 230°C)*, so you can move straight onto styling.
- Activate with heat: Lock in the effects of the serum with heat by blow-drying and straightening your hair.
*Instrumental test after application of the serum
One of the key benefits of keratin for hair is helping extend the vibrancy of your colour. Want to learn more? Our guide on how to maintain colour-treated hair will help.
