The same goes for the powerhouse ingredient in hair. The Peptide Prep shampoo by K18 is a reparative, moisturizing shampoo that eliminates build up via salicylic acid and strengthens weak strands with peptides.Size: 8.5 ozSephora rating: 4.6 5 stars An ELLE contributor says: goldensgooseser.com On wash days, nothing gives my hair a fresh start like the K18 Detox Shampoo. I used to use it in...