Purifying shampoo for hair with tendency to oiliness. Lightness and suppleness. Greasy hair is heavy. The scalp and roots of hair look shiny. Oily scalp and hair is characterized by greasy roots and an unpleasant, general oily look. Hair is weighed down by dust captured by sebum, which is over-abundant on the hair's surface. This issue is caused by hyperactivity of the many sebaceous glands in the scalp that secrete sebum (which surrounds the hair shaft), giving the hair a greasy appearance.