Prevention Is Better Than Oxidation When something comes in contact with oxygen, oxidation happens. Like when we cut an apple into pieces, after sometime we notice that the Apple has turned brown, this is because of its exposure to oxygen. In same way, our makeup ingredients consists of certain minerals, which when exposed to oxygen starts makeup oxidation. However, the time may vary for different objects. Not only the mineral content in our makeup such as titanium oxide, zinc oxide etc. but also when the natural oil in our face mixes with the makeup, it reacts & oxidation may be noticed.