A cold rain fell throughout the night and into the early morning of Nov. 7, 1811. Along the banks of Burnet’s creek in the Indian Territory – later to be known as Indiana – 1,000 U.S. troops camped on little more than 100 acres of high ground near where the Tippecanoe and the Wabash rivers flow together. Their commander sensed an ambush in the making, despite the promises of a truce by Tenskwatawa - chief of the Shawnee – just the previous day. Several hours before dawn, the war cries of the Shawnee and other confederated warriors, accompanied by bullets, confirmed he was right.
Constructed of 440 sections, each 8 feet in length, the fence surrounds the entire battlefield, running a length of almost three quarters of a mile. A large cast-metal eagle with a wingspan in excess of 6 feet perches on the archway of the main entry gate in the fence(Image 1). The fence is itself a monument, built at a time when “craftsman” truly described a man’s work. During assembly, pre-crafted vertical pickets were placed in the top, middle, and bottom horizontal rails of the fence, held in place with a small iron “bead” welded onto the picket(Image 2).
As part of the effort to examine the available options for restoration and preservation the board contracted Thomas M. Meredith, Architect, LLC. Meredith evaluated the latest technology available for the protection of iron structures. A coating system recommended by Sherwin Williams Industrial and Marine Coatings would eventually prove itself worthy of the application, and provide many years of protection once applied to the fence. A properly applied system consisting of a zinc-based primer (for cathodic protection), followed by a fast cure epoxy (for impact resistance), and finally a top coat of hi-solids polyurethane (for color and finish) would create a lasting coating capable of withstanding the elements for many years to come. The life cycle of this package has been proven on countless bridges and similar structures. As with most painting applications, proper surface preparation is critical to the success of the coating’s application. In this case it was determined by Sherwin Williams that an SP-6, “near white metal” finish was required prior to coating.
The way this fence was constructed it is rigid when in place, but very flexible and prone to damage if disassembled. Further, the bolts and nuts used in the original construction - historically significant themselves - would surely be damaged in the disassembly process due to their corroded and fused state. Lastly, the fence had actually become a part of the battlefield grounds. The trees in the battlefield area are in very close contact with the fence(Image 5). In fact, in some areas the fence is actually embedded in the trunks of growing trees(Image 6). Due to the intrusive nature of this method of restoration, Thomas and the board determined that this would be inappropriate for a monument of this nature and significance, and another search began.
Media blasting involves “throwing” abrasive materials with compressed air at a surface to clean it. Blasting would allow the fence to be stripped and coated on-site and in-place. Containing the blast process and providing a controlled environment for the coating process would both be challenges. The bigger concern with this on-site option was the possibility of damaging the iron with an over-aggressive blasting process.
By February, the process had been tested at a local contractor’s shop on one of the gates that had been removed for other repairs. It was immediately apparent that the baking soda media was able to remove paint and surface corrosion. This was, however, not enough to meet the SP-6 requirements of “near white” metal. The addition of a small percentage of aluminum oxide to the mix was all that was required to meet the SP-6 specifications. In most areas a mixture of 90 percent baking soda and 10 percent aluminum oxide was sufficient to meet the requirement while removing minimal excess metal. In areas of excessive rust, mixes of up to 50 percent aluminum oxide were tested. Although the blasting proved very effective, it was apparent to all that an effective means of containment would need to be employed.
The hands-on work of restoring the fence officially began on June 30, 2008(Image 7). It was determined that two sets of 90-foot-long scaffolding would be set up end-to-end over the fence. These two long sections were wrapped in reinforced plastic, creating two contained areas – one section for blasting, one section for coating(Image 8). Each section was placed under negative pressure using axial fans and dust socks to “turn over” the air and capture the process debris(Image 9). Blasting would take place in the first containment.
Impact to the environment was absolutely minimal. According to Jason Strassburg, project supervisor for Shelby coatings, “Deer and other animals were a constant reminder that this job was in the woods, and the people, always friendly and encouraging, a reminder that this was a public park.”
Everyone involved with this project felt a sense of pride and accomplishment with the completion of the fence restoration. Battlefield visitors are overwhelmingly supportive of the restoration.
“The results that we achieved were beyond anything we expected at the outset,” Nail said. “The blasting proved capable of finishing the fence, with minimal damage to fence or battlefield, and the coating is appropriate to this monument, protecting it for generations to come.”