Pushing the boundaries of stainless steel fabrication
A. Zahner Company is an internationally acclaimed engineering and fabrication firm headquartered in Kansas City, Missouri, USA. Ever since it was founded in 1897, this family-owned business has been at the forefront of cutting-edge design and metal fabrication for art and architecture. Under the management of L. William Zahner, who is President & CEO, the company began a rapid shift from regional projects to high-profile architecture. By Matjaž Matošec
As a fourth-generation company leader, Mr. Zahner has an inherited affinity for working with metals. He received his Bachelor of Science degree in Civil Engineering from the University of Kansas. He is the author of two books on metal in architecture as well a contributor to numerous articles and books on metal restoration and fabrication.
When asked about the history of his firm, Mr. Zahner explains, “Zahner started out in a bustling town in southern Missouri, near Joplin. At the end of the 19th century, Joplin was a zinc mining town. The company was started by my great grandfather, Andrew Zahner whose father had migrated to the United States from the Basel region of Switzerland in the 1850s. The company manufactured and installed cornices, the decorative ‘hats’ on buildings that were in style in this period. He moved the company to Kansas City, Missouri, where his brother had a very successful business making iceboxes for homes. He continued working on cornices and tin roofs for the wealthy homes at the time. Today we have two permanent facilities, one in Kansas City, Missouri–our headquarters–and one in Grand Prairie, Texas, a township just outside of Dallas. We employ over 200 people and focus on providing our clients with the highest value possible in architectural metal work. Perhaps the biggest change that my generation has brought to Zahner, essentially re-inventing ourselves, is high-level engineering and research and development of new systems and processes. We have eight patents and at least that many on the way.”
Mr. L. William Zahner, CEO and President of A. Zahner Company.
Architectural appeal of stainless steel
In Mr. Zahner’s view stainless steel is the most versatile of all the architectural metals available. Corrosion resistance, strength, durability, low maintenance and formability are among its defining and most valued characteristics across all industries where it is used, but the one feature that makes this material so appealing to architects and designers is its appearance. Mr. Zahner emphasises its inherent beauty almost poetically, “Stainless steel demands precision. I like to say virtuosity–a term usually used in reference to artistic pursuit, but equally well suited to describe what is needed to achieve incredible work out of stainless steel. When you see it done well, like when you hear a great orchestral perfor- mance of Bach, you know it. It is the metal of art.”
At Zahner they work with all metals–copper alloys, aluminium, titanium, zinc, steel and even, on rare occasion, silver. Designers approach the company with their ideas, which are then considered from different perspectives. “The choice of metal is secondary to the aesthetics, performance and cost,” explains Mr. Zahner. “As we get deep into what the designer hopes to bring to their client we often find that stainless steel offers a plethora of choices. It often boils down to whether the design calls for a gentle aging of the surface, what you might get from copper alloys, zinc and weathering steel, or if the design requires a stable, predictable appearance.”
He continues, “For the stable, predictable surface appearance, it is difficult to beat stainless steel. The other choices are titanium and painted aluminum or painted steel. With titanium, the value proposition is hard to overcome. The cost per surface unit is a multiple of that of stainless steel, while the corrosion resistance parameter in today’s cleaner environment lacks any significant benefit over stainless steel. Painted surfaces pose environmental issues both at the time of application and at the time of recycling. You can achieve an enormous variety of colour with pigments, but for how long? There is an inherent limitation of pigments. Additionally, we have found that the cost of high-quality painted aluminum surfaces is nearly the same as that of stainless steel at the current prices. The remarkable ability to achieve colour on stainless steels via interference oxides and physical vapour deposition processes coupled with modulation of the tones by means of surface finish treatments means that no pigment can come close to achieving the intense, real metallic appearances.”
The Petersen Automotive Museum in Los Angeles, California, designed by Kohn Pedersen Fox Associates. This recently renovated museum encases a red-painted aluminium rainscreen whose custom-corrugated profile wraps the existing structure. This acts as the backdrop for a series of stainless steel ribbons that wind across the exterior.
Photos © A. Zahner Co.
Fabrication demands knowledge and skill
The most common grades used in architecture are 304, 304L, 316, and 316L, with extended corrosion resistance in environments subject to chlorides being the determining factor. But the knowledge needed to translate a design concept into a feasible, fully functional and aesthetically pleasing reality extends far beyond the issue of corrosion. For this reason, Zahner employees are trained to understand, among other things, the surface behaviour of the metal–from ordering the metal to arrive from the same heat or anneal batch to insure colour consistency to cleaning the surface once it is installed. Once the metal and finish are specified, they often create visual prototypes of the surface and test them so as to avoid any unpleasant surprises.
Knowledge, skill, as well as technology, are the keys to success and innovation. Mr. Zahner elaborates on the importance of these assets: “There are many characteristics of thin metals that need to be understood. When dealing with stainless steel, a good knowledge of the higher tensile strength and the shaping and welding processes is essential. A certain skill level is also required. Our equipment and processes are geared to the harder, tougher materials such as stainless steel. Many fabrication facilities are not and so they may say to a designer that stainless steel is more expensive, difficult to work with, etc., but these in fact are simply limitations of their processes.”
He provides the following example, “The Broad Art Museum in Lansing, Michigan, is covered in two-mm-thick stainless steel. The edges are V-cut to create the tight folds, which the late Zaha Hadid wanted on her design. We welded the corners and polished the surfaces to match. We incorporated some robotic welding with human welding techniques. The result is one of the more remark- able surfaces ever created. In the beginning, during design development, however, the consultant on the job and a few others said it couldn’t be done. ‘You should use composite; the surface will oil can and distort; welds will be visible and will corrode.’ These were some of their recommendations and concerns. We produced a prototype complete with V-cuts and welds, and so did the composite company we were competing with. The composite had open joints and sealant. The surface was painted aluminum. There was no comparison. The price was not that much different but the quality of the surface created with stainless steel looked like a jewel.”
The Broad Art Museum
Advice for industry professionals
Zahner Company works with a variety of clients, from developers and building owners to architects, designers and artists. Mr. Zahner has the following advice for industry professionals, “Work closely with the fabricator–the good, honest ones, and let them know if something has changed in the production of the metal. Often we can still work with it and make it a non-issue, as long as the problem is not concealed.
Also, stop denigrating one metal in comparison to another in industry presentations. All metals should be embraced in architecture and design. Because of its versatility and with stainless steel’s many qualities, it will always float to the top and get more than its share. Casting doubt into the mind of designers can push them to alternative materials.”
A Look into the future
When asked about the most recent technological developments that have opened up, or promise to open up, new possibilities for the use of stainless steel in architecture, Mr. Zahner replies, “We are just beginning. I turn 61 this year and fear that I will miss the fun. Stainless steel holds the keys to the future. Trends in roofing surfaces, recycling requirements, developments in welding technology, polishing and finishing offer enormous potential for creative applications of stainless steel. I hope to see non-fingerprint coatings become available to the open market and still wait for the introduction of an effective and consistent cleaner for stainless steel surfaces. Once a project is complete we need excellent means of enabling our clients to keep their work clean. As already mentioned, we have several intellectual properties involving metal systems. One example is TesselateTM, a modular screen system enabling programmed movement of metal surfaces, which utilizes stainless steel because of its inherent strength and finish on all sides and edges. We are also working on modified finishes to take advantage of the reflective character of the metal. New laser technology is allowing us to create incredible, ornate features with stainless steel. We have just scratched the surface on textures and reflective characteristics that can be introduced to stainless steel.”
Immensely passionate about this material and always positive in his outlook, Mr. Zahner concludes, “Stainless steel has been in architectural use for approximately 100 years. In the last 20 to 30 years we have seen a tremendous growth in the use of stainless steel in architecture. I believe we will see stainless steel become the material of choice for many of the major architectural jewels of the future. Like I said, it is the metal of art.”