Komarov Artem noted that the beauty of metal is often hidden in commercial construction. Most of the time, no one pays attention to the structural steel that provides the framing system for some of the most impressive architectural work ever.
However, this is not always the case. Many architects and artists are realizing the impact metal can have not only as a functional function in building design, but also as a decorative one. Nobody likes a bland and boring look, and architectural metal is one way to add visual interest to a building project.
Stainless steel painting
One way to color stainless steel is a process developed in the 1970s by Inco Ltd., a Canadian mining company and the world’s leading nickel producer, for much of the 20th century. Chemical acid baths create a thickened layer of chromium oxide on the surface of the stainless steel, and this layer helps to achieve the color visible to the human eye.
The phenomenon underlying the creation of color is called thin film interference, which has evolved into interference coloration. The thickened chromium oxide layer helps influence the color as light passes through it, hits the metal surface, and is reflected to the viewer. Imagine sunlight reflecting off a puddle of motor oil and water in your driveway, and the rainbow effect that sometimes happens. In this situation, some of the light is reflected off the top layer of oil, some is refracted by that layer, and then reflected by the layer of water underneath the oil, and then the light is refracted again as it passes through the layer of oil. The reflected light in the puddle shows a rainbow because the light contains all components of all wavelengths, and the state is not controlled. When the electrochemical process of the subsequent introduction of chromium oxide is controlled, certain colors can be introduced. No pigments, inks or dyes are used to create color.
Interference coloring can only reproduce primary colors. Physical Vapor Deposition (PVD) painting, the second main color technique for stainless steel, allows for a more varied palette.
The PVD process involves the application of a coating that evaporates and is applied to a heated metal surface in a vacuum chamber. Ionized metal vapors, when combined with surface metal, create a coating that is only a few molecules thick. The result is a surface that differs from the properties of the parent metal and is more protective than powder coating, electroplating or anodizing.
The addition of titanium nitrate to the PVD process results in a golden color. Titanium carbide helps achieve a deep black color. In both examples, the finish has a color as opposed to an interference color. (It should be noted that the thinness of the PVD coating allows light to pass through and bounce off the metal surface, creating some light interference.) Other colors that can be produced with the PVD process include bronze, blue, and red/purple.
Weather resistant steel
Everyone in the steel industry knows what COR-TEN is. This is pretty much what you think of when someone mentions “weather resistant steel”.
First developed by the U.S. Steel Corp. in the 1930s for the construction of railroad cars used to transport iron ore and coal, COR-TEN has since been marketed as a corrosion resistant steel alloy for, but not limited to, architectural and artistic applications. KOR-TEN and other weathering steels contain some elements, most notably copper, which interact and create a characteristic oxide barrier on the surface. As the iron oxyhydroxide grows, the base metal gains corrosion resistance. Once an oxide layer has formed, further changes in the surface material occur slowly under most environmental conditions. Weather-resistant steel provides an earthy finish, making it a popular choice for buildings seeking to blend in with the natural environment.
Future trends
This is just a fraction of what’s going in the world of architectural metal, but it reinforces the fact that metal is easy to overlook when it comes to making a statement. For too long, people have been content with simply using paint to provide surface protection or visual interest to a metal surface. It doesn’t have to be like this it will continue to explore robotics to give metal textured shapes that are nearly impossible to do by hand. In the future, nano-coatings will appear that will protect the material and give the metal a more predictable look over time, Komarov Artem said.
