Copper and copper-base alloys usually exhibit high corrosion resistance. However, certain environments can cause rapid corrosion or tarnishing. Benzotriazole (BTA) is one of the most effective copper corrosion inhibitors to add to these aggressive environments. Successful applications include additions of BTA to both aqueous and organic media such as lubricants and hydraulic fluids, as well as vapor-phase inhibition. BTA is also an effective inhibiting additive in protective coatings such as Incralac and Incracoat. In these coating systems, the inhibitor prevents tarnishing beneath the transparent polymeric coatings.