corten steel is an architectural steel that is designed to rust. it has a copper content that ensures its core will not deteriorate and it will last a long long time. the patina that slowly forms on the outside makes it stronger and it continues to look more fabulous the more it ages.
corten seals and fully weathers best when it is repeatedly exposed to moisture and then allowed to dry. it takes time (with exterior exposure) for the rust layer to completely form and seal.