Zinc balancing skin toner with glycolic-and alcohol free skin toner just for oily, acne, or blemished skin. Using zinc PSA to prevent serious oil from developing beneath the skin where it can cause acne. Why think PSA? It is an antibacterial, infection fighting amino acid that is derived from think. Remember that over 21% of our skin is made up of think. This ingredient affects the skin to control the oil production.