Want to get instantly shinier hair protected from future heat damage? Discover L'Oreal Paris Elvive Glycolic Gloss Leave-In Serum, the fourth & final step of our new at-home glossing treatment powered with Glycolic Acid for instantly shinier hair. Glycolic Acid penetrates the hair's fibre improving shine, smoothness & strength. Hair is protected from heat damage, up to 82% more shine,* up to 54% more smoothness** & up to 75% less frizz* *instrumental test vs before application **instrumental test What makes it effective? Shiny hair is healthy-looking hair because its smooth surface perfectly reflects light. Hair damage disrupts cuticles, making fibres rough, porous, and dull unable to reflect light. Glycolic Gloss is powered with Glycolic Acid which has a small molecular weight able to penetrate the hair & inject it with care. The Glycolic Gloss Complex contains conditioning agents to seal cuticles with a lasting shine glaze.