Where will you find a giant bean sculpture that has become a major attraction in a cosmopolitan city?
Try the Millennium Park in Chicago and look for the Cloud Gate.

Millennium Park’s Center of Attraction
Cloud Gate is one of the most unique and largest stainless steel sculptures in the world found at the promenade at Chicago’s Millennium Park in Chicago, Illinois. It was formally unveiled and opened to the public on 15th May 2006 and has since become one of the city’s main tourist attractions.
Stainless Steel Used In Outdoor Sculptures
The sculptor behind this interesting work of art is Anish Kapoor, one of the many sculptors and artists around the world who started using stainless steel for their artworks. The 1970s marked a new era for this unique material. The material’s inherent durability and ability to withstand the corrosive elements of nature had made it particularly suited for use in outdoor sculptures. What made stainless steel material extra special is its reflective properties which adds the extra visual dimension to the art piece.
Cloud Gate: Fabrication Challenges
The humongous sculpture was brought to life through the hard work of over 100 metal fabricators, technicians, engineers, and welders. The construction of the outer shell necessitated the engagement of two companies – California-based Performance Structures, Inc. (PSI) and Illinois-based MTH. The small scale model was created by Ethan Silva of PSI who had extensive experience in creating shell structures on ships and art projects.
The challenge, according to Silva was on getting the huge plates to the curvature in as high a precision as possible. That required accurate forming and fabrication of the rib-system framework for every plate.
The succeeding construction procedures present different types of challenges such as how welders used flux-core process to stitch-weld the curved plates onto the rib system; hand-grinding and machine-milling of the plates to the thousandths-of-an-inch to achieve a perfect fit when putting the plates together; checking the dimensions using laser scanning equipment; and the tedious work of polishing the plates and applying protective film to make the smooth and mirror-like surface.

Cloud Gate: Installation Challenges
The other company, MTH which is based in Chicago was in charge of installing the plates and framework fabricated by PSI. MTH together with some of the PSI workers set out to install and join the pieces of the superstructure together. It was time for MTH to deal with the installation challenges including:
- Installation of the truss system for the 30,000 pound substructure with two large O-shape rings fabricated from 304 stainless steel. The frame was field-bolted and reinforced with stick welding and gas metal arc welding (GMAW).
- Assembling the shell over the substructure using a suspension system where every plate had its own hanging support system to put it into place. MTH engineers said it was necessary so that there is no over-stressing on any joints on the system.
- Plasma welding to provide the strength needed for the substructure. Welders had to weld from only one side on the exterior.
Highly-Polished, Seamless Stainless Steel Sculpture
Cloud Gate is fabricated from 316L stainless steel plate. Kapoor used 168 pieces of 1 cm thick plates seamlessly welded together. The elliptical sculpture weighs 110 tons and measures 33 ft x 66 ft. It is highly polished into a smooth rounded shape that resembles a giant drop of liquid mercury. Where joints were fastened together with special washers like 300 series stainless steel flat washers, no one could guess where they are exactly. Kapoor succeeded in masking off over 2,500 lineal feet of seam welds and achieving a highly polished finish. The sculpture’s seamless surface is the result of thousands of hours of polishing.
A Thousand Year Life Span
Part of the contract for the Cloud Gate requires the constructed piece to last 1000 years. And to do that, a highly meticulous maintenance program has to be reinforced which includes:
- Wiping down the lower section of Cloud Gate twice a day by hand
- Cleaning of entire sculpture using 40 gallons of liquid detergent, twice a year
- Daily cleaning using a Windex-style cleaning solution
Interactive Piece Of Art
For the Millennium Park, Kapoor said he wanted to make something that invites the Chicago skyline – something that would allow people to see the clouds floating in, and the tall buildings reflected in different angles. His concept included having some kind of a gate where the viewer or visitors can enter into the deep chamber that does the same thing to their reflections as the exterior mirror-like surface does to the city view and skyline.

Cloud Gate represents Chicago skyline splendor as the ‘bean’ plays tricks with the light and the sky reflecting and distorting;
- the skyline of Michigan Avenue
- the people nearby
- the buildings and structures around
Visitors Are Part Of The Art
It is elegantly massive – without any color of its own. The richness of the experience one can have in his encounter with Cloud Gate will depend greatly on the people around who likewise anticipate a unique interaction with the piece of metal. Kapoor has included an interactive artwork right in the middle of the Millennium Park where viewers and visitors actually become part of the art. They can also choose to just stand back and enjoy the various views offered by the sculpture to the curious onlookers.
How Cloud Gate Ended Up In Chicago
Cloud Gate is Kapoor’s first public sculpture in the United States. It was completely designed and fabricated in California. It was originally intended to be Lurie Gardens’ centerpiece but park planners were protective of the garden. The sculpture was taken apart and shipped to Chicago for reassembly at the Millennium Park.
Shouldn’t Millennium Park thank the Lurie Gardens’ planners for refusing Cloud Gate and making it the new symbol of modern Chicago?
Article Sources:
http://www.chicagoarchitecture.info
http://www.aviewoncities.com
http://gochicago.about.com
http://www.chicagotraveler.com
http://www.brownmac.com
I have seen this abstract piece of art in a music video and on the MTV reality show, The Real World: Skeletons. I presume that the skeleton of this structure is made of some sturdy type of metal and the skin is of a more flexible skin material with a reflective side – much like the statue of Liberty. This piece of art is an interesting back drop for photography and video production and you can bet the local art school and production students use it for some of their projects.
The metal fabricators and welders who constructed the outer shell must have had a heck of a time shaping it to those smooth, precise curves. Those who polished the plates to the point where they achieved a mirror like surface must have earned their money, including overtime wages. Nevertheless, no matter how long it took and how much effort it cost, the finished product is well worth it. It is a unique experience to see this in person.