Terne II used zinc in place of lead for environmental reasons. Today's main reason and benefit of the tin coating is its aesthetic behavior. Tin develops a natural matte grey patina when exposed to the elements. The result of the weathering process depends on the environment and climate conditions present. Depending on the environment and atmospheric conditions different substrate alloys are used. The stainless steel alloy 439 is ferritic and is used for normal environments; for coastal applications, the austenitic stainless steel alloy 316L is used providing an increased corrosion resistance to chlorides.