K18 is a hair treatment that is designed to repair damage caused by bleach, color, or heat and add strength, softness, shine, and bounce to hair. It works at a molecular level to repair the polypeptide chains that have been broken and reconnect the disulfide bonds. K18Peptide is the products star ingredient, which mimics the structure of the hair’s natural keratin to boost moisture and promote thicker hair. The patented peptide is also designed to repair broken keratin chains, which improve hair strength. K18s hair mask is a leave-in treatment that is used after shampooing and before styling. It is applied to towel-dried hair and left for four minutes before styling. K18 is safe to use on all hair types and textures, including curly and coily hair that has been damaged due to chemical treatments. K18 is a less straightforward treatment system than others, and it is recommended to skip the conditioner after shampooing the scalp to reap the benefits. K18 is clinically proven to repair damaged hair after just one 4-minute in-salon treatment.