plating, anodizing, & finishing Q&As since 1989
Finish/sealer for intentionally-rusted structural steel
I am an architect-builder designing and building a house in the Utah mountains (a high and dry climate where buildings sustain low to moderate weathering but intense ultraviolet exposure). As an intentional feature of the design I intend to let the exposed parts of the steel structure and the steel windows and doors rust, but of course not to the point where they lose strength. What would one of the experts recommend to stop and seal the rust? I rubbed some Linseed Oil [affil. link] on a lightly-rusted steel sample , and it looks great, but I don't know how long it will stand up to the conditions on site. We can live with periodic maintenance, but we want the finish material to be as durable, transparent, and protective as possible without discoloring the rust.John V. Lewis
Babcock Design Group - Salt Lake City, UT, USA
There is a family of high-tensile steels called COR-TEN. It will oxidize and turn orange, but in the environment you describe, will not rust. No need for further finishing. Sometimes it is misspelled coreten or corten, but on the US Steel web site, it is COR-TEN all in capitals. It is used in everything from sculpture to big honking bridges (like the Port Mann bridge near here).
Go to the US Steel web site, and search for COR-TEN.
- Vancouver, BC, Canada