Zinc Sulfate Worst Preservative No known benefits Zinc Sulfate description Chemical compound resulting from the interaction of zinc with sulfuric acid. There is little research showing this to be beneficial for skin. The information that is available shows that it can be a skin sensitizer when used in large amounts. A small amount of zinc sulfate is sometimes used in high-strength vitamin C treatments to stabilise the vitamin C (typically seen on the ingredient list as ascorbic acid). In these instances, the zinc sulfate is unlikely to be a source of skin sensitivity.