Exfoliating dead skin (removing keratin) makes skin smoother.
Tips
usage
角质 spans biology (keratin in skin/nails/hair) and skincare advertising. The compound 去角质 (qù jiǎozhì, 'remove keratin') is the standard Chinese term for chemical or physical exfoliation - you'll see it on every Chinese-market beauty product.
memory
角 = horn, 质 = substance/material. Literally 'horn-substance' - the same protein that makes animal horns also forms human nails and hair.
