por-15 45818 gloss black top coat - 14 fl. oz. (4 pack) por-15 por-15 gloss black top coat aerosol is a direct-to-metal (dtm) paint designed to work incredibly well in all applications where there is a need to help preserve substrates susceptible to corrosion. under exterior exposure por-15 top coat has exceptional long-term sheen and color retention. por-15 top coat can be applied directly to metal substrates or previously painted surfaces, with no need for a primer or undercoat, and is formulated to form a robust barrier that sheds moisture to provide long-lasting protection. por-15 top coat provides excellent adhesion and when used over por-15 rust preventive coating, works to provide a permanent barrier to corrosion. warning: this product can expose you to chemicals which is [are] known to the state of california to cause cancer and birth defects or other reproductive harm.