Public Art Conservation:
Inside the Old Post Office Building at 100 Pennsylvania Avenue, NW in Washington, DC hangs one of the great Public Art commissions in the United States: Robert Irwin’s SHADOW PLANES. It was commissioned for the building, to be enjoyed by the public, by the U.S. General Service Administration (GSA) through its Art-in-Architecture Program.
GSA Public Art commissions are made through selection panels that include as members an architect for the building, art experts, community stakeholders, and members of the public for broad representation for the artwork selections.
48 SHADOW PLANES measures an impressive 110 feet high and 135 feet long, and consists of 48 fabric planes (or panels) suspended by wire ropes. And that 110 feet of artwork height has its lower edge already about 40 feet above the atrium floor. The artwork is suspended from the enormous skylight covering the nine-story high and enormous atrium – a kind of covered cortile.
The skylight above, impressive on its own, is a complex web of painted cast iron and 1,000 panes of glass. The artwork’s 48 “planes” are each made of loosely woven, thin white scrim material selected purposely to have an ethereal, ghost-like presence and low visual dominance. On these faint planes are cast the ever moving dark shadow shapes made by sunlight coming through the glass and iron network above. This commission was a brilliant modern concept and an addition so surprisingly complementary to the old architecture dating back to 1899.
SHADOW PLANES was commissioned when the Old Post Office Pavilion (originally the “Old Post Office and Clock Tower”) underwent a major renovation in 1983 that included a food court filling the atrium floor and retail shops on the lower floor level. The construction of that renovation made it possible to install this massive work of public art above the food court. The Old Post Office Pavilion became a highly popular tourist attraction for its building tours and the food court.
As has been widely reported, the cost to the government of maintaining such a large and old building became so great that a solution was found to preserve the building by leasing it as a hotel. In 2013, the building underwent a 200 million dollar renovation to become Trump International Hotel under a 60 year lease.
By 2013, Robert Irwin’s Public Art SHADOW PLANES had hung above the food court in that enormous air space of the atrium for 30 years – without maintenance cleaning. How could one clean it? It was unreachable as the atrium was fully occupied and no aerial lift large enough to reach up nearly 200 feet could be brought into the building. It could have been lowered by its five winches but there was never enough open floor space to receive the artwork due to food court installations.
Dirt, grease, and dust carried from below on upward moving warm air currents for 30 years heavily sullied and darkened all components of the hanging artwork. The white and ethereal panels became gray-brown in color making the cast shadows less distinct and making the planes the predominant visual feature of the artwork instead of the play of shadows – essentially ruining it’s artistic purpose.
Converting the Old Post Office Pavilion into a major hotel and undergoing approximately 200 million dollars of renovation and alteration construction essentially saved this great work of Public Art. Such a disruption created a window of opportunity to remove the hanging, clean it, restore it, and reinstall it. The GSA tasked McKay Lodge Art Conservation Laboratory, Inc. with this work.
Not surprisingly, Trump moved very fast in starting the renovation, and then pressed very hard on everyone for a fast completion. We were given a very narrow window of opportunity to remove the enormous artwork, bring it to our facilities for the conservation work, return it and get in back in place. This all took place over the latter part of 2014 to early 2015.
There was not time for an initial comprehensive plan. The plan evolved as work progressed. Work and GSA financial support for the project kept pace with every changing and tightening deadline to get it back up and get ourselves out of the way.
And then there was the big worry: would Donald (or Ivanka) Trump let it back into their new lobby, so newly and gorgeously designed, to hang over the swank Benjamin (the so-named bar and lounge covering the atrium floor – named after Benjamin Franklin)? The answer was “No.”
But at some point, perhaps after Ivanka Trump spoke with the artist Robert Irwin, and possibly art advisors, it became a “Yes.” And after all, its continued presence as a Public Art commission for this building was a requirement in the 60 year lease.
The sculpture SHADOW PLANES is a series of fabric panels arranged in a grid pattern (8 columns of 6 panels). The grid structure is comprised of wire roping to which metal bars holding the fabric panels are attached. An aluminum top beam suspends the entire grid assembly with another beam located at the bottom of the artwork acting as a weight
The atrium of the Old Post Office was originally the mail sorting room of the Old Post Office. A network of girders and catwalks were installed at the third-floor level to allow post office supervisors to observe and monitor the workers from above. The work hangs about ten feet above this structure, and some forty feet off the floor, centered in the middle of the atrium.
The first phase of the work was removing the artwork from the building. The sculpture is hung from the building’s trusses high above the atrium floor using wire rope attached to five winches located on the ninth floor behind the railings
The width of the artwork exceeds that of the network of girders and catwalks. A scaffolding platform was erected on top of the catwalks to be a staging area for disassembly. Through a coordinated effort, all five of the winches were operated simultaneously to lower the artwork. Once it was lowered, the top portion of the components, formerly out of reach, were then inspected.
The first reachable element of the sculpture was the lower beam. It was found to be stained and had a thick buildup of settled dust and grime. It was also scratched and showed signs of water staining. The water stains and streaking associated with them indicated that the skylight above must have been leaking for quite some time.
Two 6 x 6-inch aluminum square tubing, one on top of the other, form the whole bottom beam. Each layer consisted of four end-connected 30-foot-long sections and one section that is 5 feet 6 inches. The wire ropes that the fabric panels attach to terminate at this beam.
The beam was broken down into its smaller components and lowered down to the atrium floor of the building.
As the artwork continued to be lowered by the winches, the fabric panels together with their metal “stretcher bars” and the wire ropes were carefully folded along the width of the scaffolding
At the top and the bottom of each fabric panel are pairs of horizontal painted metal bars. The bars are screwed together with 15 countersunk fasteners with the fabric “pinched” between them. At the end of each set of bars are two countersunk fasteners with a set screw located on the opposite side of the bar in-between the two fasteners. The wire rope feeds between these two fasteners, and the set screw attaches the metal bar to the wire rope. The assembly of the panels, bars, and wire roping were all left assembled to use as a reference for sizing and spacing during treatment.
Inspection of the fabric panels revealed that the once ivory, near white colored panels had become brown with dirt. They had acted as air filters for the past 30 years. Some of the panels had water damage and staining due to the leaky skylight.
The upper beam was then lowered to the platform. Unlike the bottom beam, the upper beam was a single layer comprised of a 6 x 3-inch aluminum rectangular tubing. The top beam broke down into five sections each 25 feet long.
The artwork was then packed, and transported to McKay Lodge Art Conservation Laboratory for treatment
The metal bars, wire rope, and the fabric panels were unpacked and inspected. The wire roping was extremely soiled but in good structural condition. The metal stretcher bars were in good condition structurally. However, the paint coating was in poor condition with a build up of grime and numerous losses; corrosion had begun to form in these unprotected areas. The fabric panels as noted were discolored due to soiling and water staining.
Past assessments and documentation from the artist indicate that the scrim material that makes up the 48 panels has a limited lifespan and were expected, somehow, to be replaced. Thus, a reserve supply of enormous rolls of replacement fabric were located in the GSA fine arts storage and transported to McKay Lodge, Inc. facilities.
After documenting the overall size, positions and spacing of the fabric panels, the panel sections were then disassembled, and the metal bars removed from the fabric. All of the fabric panels were of the same dimensions (8 feet wide and 8 foot 3 inches in length). We fabricated a cutting jig to cut the panels straight and ensured consistent sizing. The replacement fabric was then rolled out, new panels cut, and immediately packaged in protective tubes, to protect them from being soiled or damaged.
The disassembly of the metal bars revealed a strip of double sided tape on the inner surfaces. We determined that the purpose of the tape was to act as an adhesive to aid in holding the fabric material when “pinched” between the bars. The tape was removed and the bars were prepped for paint removal.
The wire rope, although in good condition structurally, was so soiled that cleaning it would have been cost prohibitive. All wire rope was replaced with stainless steel roping of the same strands, diameters and lengths as the original.
The beams were soiled, stained and scratched. Originally, they had a clear anodized finish and appeared gray in color. Anodizing is an electrolytic passivation process commonly used on aluminum. The passivation process hardens and protects the aluminum from corrosion.
Anodized finishes are not repairable, and the parts must be re-anodized if that finish and color are desired. Anodizing requires the parts the be immersed in tanks containing an acidic solution. Unfortunately, no anodizing company located in the United States can accommodate parts that are 30 feet in length. So either the beam sections would have to be replaced, or a paint coating would have to be used.
Replacement of the beams would be quite expensive, so the artist was contacted to gain approval for painting the beams. The artist approved the paint coating “so long as it had a neutral gray color.” An appropriate color was selected. The beams received an orbital sanded finish and were then coated using a using a direct to metal (DTM) acrylic paint from Sherwin Williams.
A structural engineering firm was engaged as part of our contract. The firm was given the task of evaluating the existing rigging, hardware and attachment systems of the artwork. The structural review identified the need for a new set of winches. The original winches were of a simple industrial design and were severely underrated for the load the artwork produced.
Updates in building codes and safety requirements dictated the need for a winch that was theatrically rated. Theatrically rated winches differ from industrial types by including an internal braking system to prevent the load from releasing suddenly, and are the only ones that are approved for hanging loads above pedestrian traffic. These winches were ordered from Thern Inc., a leading provider of theatrical and industrial winches.
The original winches were only 6 inches wide and carried a load rating of 800 pounds each. The structural calculations indicated that these winches were undersized and the actual load rating needed to be 1500 pounds. New winches were then custom made by Thern to meet the necessary specifications of load rating and size. We fabricated custom made bases from 1-inch- thick steel plate. These steel plates not only provided a solid and secure mounting platform for the winches but also act as a counter weight offsetting the load of the sculpture.
The floor of the building where the winches are anchored is not solid. It is a hollow structure made from terracotta. This “flat arch floor” as it is known was quite common in buildings of this era. Because of this, the engineer specified an epoxy anchoring system from Hilti Corporation (HIT-HY 70). This system is a state of the art epoxy anchoring system that is strong, reliable and is commonly used in seismic retrofitting of buildings.
These anchors were installed into the existing floor and after curing subjected to a pull test. A “pull” test is used to verify that the anchors have been installed and the epoxy cured correctly. In this test a measuring device is installed on one of the anchors at each of the five locations and the anchor is tested with 400 pounds of tensile force. Of the five sites, only one did not pass the test. This anchor was drilled out, re-installed and tested again after curing. This time, the anchor passed. The winch plates were then moved into position and bolted down.
After the winch plates had been installed, the winches were aligned and installed on the plates and bolted down using four ½ inch bolts.
With the winches in place, the five cables that would hang the sculpture were to be installed onto the trusses located at the top of the skylight.
The original installation used a combination of beam clamps and snatch blocks to hang the sculpture. We had instructed the engineering firm to specify a new clamping system, so all components in the system were new and known to be reliable. The new beam clamps that were specified and procured were not able to be installed because they were of a different design and could not properly close due to the interference of rivets located along the trusses. The structural engineer was then consulted to either specify a new clamp or approve the use of the system that was already in place. Detailed photos were provided of the existing bean clamps, and they were deemed to be more than sufficient for reuse. The existing snatch blocks were changed for new ones of a superior design.
Access to the beam clamps and block required the services of a high reach company who provided men and equipment to “walk the beam.” After walking out on the trusses the contractor was able to simply tie off the old blocks, remove them, and replace them with the new ones. With the new snatch blocks installed, the five cables to hang the sculpture were threaded through the snatch blocks and brought over to the winches. The cables were then installed on the winches and left to hang down to the platform for connection to the top beam.
The installation of the artwork required full reassembly of the artwork on-site. All of this work had to be performed atop a scaffold platform and included the assembly of the top beam, attachment of the hanging cables to the top beam, attachment of the 16 wire ropes to the top beam, assembly of the fabric panels and stretcher bars, and assembly of the bottom beam elements.
The top beam was assembled using the same method and components as the original installation. These components consisted of the 5 top sections and four sleeve fittings fabricated out 24-inch-long sections of I-beams. These fittings were inserted into the beam section on either side of the joint and screwed into place.
The original connection from the cable to the top beam was inadequate and dangerous. The connections did not take into account that wire rope twists as it is being wound up by the winch. When the artwork was originally lowered two of the connections unscrewed themselves from the beam and detached. A new system was designed that incorporates a swivel connection so that the artwork can be raised and lowered without fear of the connections detaching. The structural engineer reviewed the system, and it was approved and incorporated.
The 16 wire ropes that hang from the top beam were then attached, and the sculpture was lifted into place high enough to attach the first (topmost) row of fabric using the newly installed winches. The fabric panels and stretcher bars were then assembled, using the original combination of double sided tape and fasteners, and attached to the wire roping using the same method as the original installation. The artwork was then raised again to the height of the second row, and so on until all 48 panels were installed.
The artwork was then raised to nearly the full height, and the bottom beam assembled, the 16 cables were attached to the beam using the same system as the original.
Attachment of the cables to the bottom beam was accomplished by running the cables through the first layer of beams and attaching a “stop” or termination to the end of the cable. The stop then was fed through a large hole in the bottom of the beam so that when raised the beam essentially rests on the termination. The second layer of beams then were bolted to the first layer hiding the holes and cable terminations. This system makes for a clean and elegant installation with no visible attachments.
Placement of the artwork was completed with the use of reference photos showing the original height of the sculpture and by using the buildings features as a reference to “level” the artwork.
Once the artwork was in place, all of the winches had drum locks fitted to prevent unwanted adjustments, and the handles were removed. The handles are currently in possession of GSA along with a master set of keys for the drum locks.
A final request was the construction of boxes to cover the five winches to the architect’s design, which we fulfilled, making the boxes and painting them in our shop.
Now we are tasked by GSA with coming up with a periodic cleaning plan. The enormous artwork no longer hangs over an atrium floor covered by food vendors and seating, now it hangs over a major hotel lobby, busy 24 hours a day, and filled with the Benjamin Bar and Lounge. Something to think about.