Many go to the salon to express themselves and achieve a look that makes them feel their best. However, the services that change hair’s shape and color can weaken the structure of hair in the process—that’s where the K18REPAIR™ service comes in. 

Today, we’re taking you through top salon services to show how each impacts hair, plus how K18REPAIR™ fortifies and repairs before, during, and after every appointment so everyone can achieve limitless expression without compromising hair’s health.

hair’s structure 101

Before we dive in, let’s do a little refresher on hair’s structure. Hair is more than what’s on the outside—it’s a complex, multilayered structure made of proteins (mainly keratin), water, lipids, and pigments.

The outer layers of hair are called the cuticle, where keratin proteins form tile-like cells that overlap and lay flat. Hair damage causes these cells to lift, chip, and break.

The cortex layer—the foundation of hair strength and elasticity—lies below the cuticle. Inside, amino acids link via peptide bonds to form long keratin polypeptide chains. These keratin proteins are crosslinked by other chemical bonds called disulfide bonds (as well as others), which link together to form the polypeptide chains responsible for hair’s strength and elasticity. Fun fact: these polypeptide chains are where the K18PEPTIDE™ works. 

But hair isn’t just protein. Internal and external lipids (fats, oils, and waxes) protect hair from the outside environment and maintain optimal moisture and melanin pigments give hair its color.

All hair can get damaged, even untreated hair. Factors like ultraviolet (UV) radiation, environmental pollutants, mechanical stress from brushing, styling, and washing, and heat from blow dryers, straighteners, and curling irons can cause damage. Chemical services like bleaching, perming, or straightening at the salon can also cause significant damage.

As this damage occurs, hair’s structure becomes weaker. 

how damage occurs at the salon

Ever wonder what’s happening to hair during salon services? We’ll explain.

Bleaching removes melanin, the pigments that determine hair’s color. That’s because bleach contains oxidizing agents (mainly hydrogen peroxide) that penetrate the hair fiber to break down melanin. But bleach doesn’t just target melanin, it breaks down the protein structures in all layers and strips away hair’s protective lipids, weakening and making hair more brittle.

Chemical perming and straightening services break the disulfide bonds in hair with high pH hydroxides (for chemical straightening) and ammonium thioglycolate (for perming). The hair is then reshaped, and the bonds reconnect. However, not all bonds re-form, leaving hair weaker and less elastic, making it susceptible to further damage.

Furthermore, heat from blow dryers, straighteners, and curling irons damage hair while styling. Applying temperatures above 482°F (250°C) causes cracks in the cuticle, leaving the cortex more vulnerable to damage. Excessive heat can break down the polypeptide chains of the cortex, causing the proteins in the cortex to melt and shrink at temperatures above 392°F (200°C). Regular hot tool users will arrive at the salon with some of this heat damage. 

how K18REPAIR™ works in every salon service 

The problem with most salon services is that they can’t target the specific components of hair that they want to change. To achieve the desired look, often they must cause damage to the entire structure of hair, weakening hair’s overall strength and elasticity.

That’s why K18 developed the two-step salon-exclusive K18REPAIR™ service to keep hair healthy during every stage of every salon service.

As we said before, all hair is damaged, whether treated or untreated with salon services prior to an appointment. That’s why treating hair before and after any service is crucial to better, longer-lasting results and maintaining hair health.

step 1: fortify hair pre-service

Step one of K18REPAIR™ is K18 professional molecular repair hair mist. 

This step is crucial because already damaged hair is more susceptible to further damage during a salon service. The PRO mist contains the K18-patented K18PEPTIDE™ to reconnect broken chemical bonds in hair, restoring up to 99% of hair’s elasticity* and creating a strong foundation for every salon service in just 4 minutes.

Just like the walls of a castle are strengthened to protect against attack, the K18 PRO mist fortifies hair against damage from chemical aggressors by strengthening from the inside out. By repairing and fortifying pre-service, hair is less susceptible to damage during the service. 

step 2: repair post-service

After the service, the professional molecular repair hair mask is clinically proven to repair damage from bleach + color, chemical services, and heat* with immediate and lasting results. K18PEPTIDE™ comes to the rescue again by fitting seamlessly into the holistic system of bonds forming the polypeptide chains deep within hair to repair and restore strength and elasticity at the molecular level.

Returning to the castle analogy, imagine that after the walls have been fortified, an attack happens. Thanks to fortification, the walls resisted much of the damage, but they still need to be rebuilt. Now, it's time to repair the castle walls to defend against future attacks.