INCI name
Zinc Oxide
Also listed as: CI 77947 (when used as a colour)
Zinc oxide is a white mineral powder. In sunscreens it reflects and absorbs UV light. In nappy creams and calming ointments it is used as a skin protectant. On a colour cosmetic label it may also appear as a white pigment, sometimes as CI 77947.
Modern sunscreen grades are often micronised or coated so that the white cast is weaker than in older pastes. "Nano" zinc oxide is regulated in the EU and must be labelled as zinc oxide (nano) when it meets the official size definition.
Zinc oxide is not a chemical filter such as avobenzone or octinoxate. It stays on the surface of the skin more than those filters do. It can still leave a white film, especially on deeper skin tones, if the grade is not well chosen.