Chapter 1: What Are Hair Bonds & How Do They Break?
Hair is primarily composed of a protein called keratin. Keratin chains are held together by several types of chemical bonds, the most structurally significant being disulfide bonds — strong covalent bonds formed between sulfur atoms in adjacent keratin chains. These bonds give hair its strength, elasticity, and shape. When bleach, chemical relaxers, or extreme heat break these bonds, the structural integrity of the hair deteriorates: it becomes weak, brittle, porous, and prone to breakage.
Chapter 2: Olaplex — The System Explained
Olaplex's active ingredient is bis-aminopropyl diglycol dimaleate — a small molecule that finds broken disulfide bonds and reconnects them by forming a new bond between the two broken ends. It can be used in-service during chemical processing (as No. 1 and No. 2 in the salon) as well as at home (No. 3 through No. 9). The at-home line is designed for maintenance. Consistent home use (weekly No. 3, daily No. 4 and No. 5) builds bond health cumulatively over 4–8 weeks.
Chapter 3: K18 vs. Olaplex — Key Differences
K18 uses a patented bioactive peptide (the K18Peptide) that mimics the hair's own keratin sequence and reconnects broken keratin chains — a different mechanism than Olaplex's disulfide bond reconnection. K18 claims to reverse 4 types of hair damage in 4 minutes. Independent testing has generally supported K18's claims for moisture restoration and tensile strength improvement.
Olaplex is better for chemically processed hair that has sustained significant disulfide bond damage (bleach, relaxers, perms). K18 is better for heat-damaged or mechanically damaged hair that needs overall keratin chain restoration.
Chapter 4: Redken Acidic Bonding Concentrate
Redken's system works differently from both Olaplex and K18. Rather than directly rebuilding bonds, it reinforces the hair's acid mantle using citric acid to lower pH and create an environment where bonds are naturally stronger and the cuticle lies flat. A gentler, less targeted approach that works especially well as a maintenance system for moderately damaged hair.
Chapter 5: Building a Bond-Repair Routine
For moderately damaged color-treated hair: weekly Olaplex No. 3, daily No. 4 and No. 5, No. 6 or No. 7 before heat styling. This is the minimum viable bond-repair routine.
For severely damaged hair: add bi-weekly K18 in between Olaplex weeks. Consider a monthly in-salon Olaplex No. 1 and No. 2 standalone treatment for accelerated repair.