Permalac NT Blackener is a transparent Black Clear Coat used to darken light colored steel or metal. It has a black patina/blackened metal appearance after applied & is often used in place of acids that have been used in the past to create a "blackened steel" look. It will protect metal from corrosion & the effects of UV, salt water air, acid rain, wind, sand, sun, dog urine,etc. for 8 years for indoor metals & 5 years for outdoor metals. At the end of 5/8 years simply wipe off with acetone & apply new Permalac for another 5/8 years of protection. Permalac NT Blackener Ultra-Flat was used to protect exposed metal in the staircase support in ASSET Restaurant, which showcases an interior related to the urban surroundings of NYC. Read about Architiect Bates Masi's project here: https://www.metalarchitecture.com/articles/metal-and-light