APT Symposium: Challenges with Preserving the Stainless Steel Skin of the Gateway Arch in St Louis, Missouri

Julie Cawby, Dan Worth, and Steve Kelley will be presenting at this year’s APT International Conference on October 25. Their session will focus on the Conservation Management Report they produced for the Gateway Arch, focused on the thoughtful preservation of the Arch’s steel skin. See their abstract below and find the full list of sessions and registration information here.

The Gateway Arch in St Louis presents numerous challenges: its sheer size and height; the use of modern metals and welding techniques; its need to remain open and intimately accessible; to name a few. These challenges were addressed in a recent Conservation Management Plan (CMP), partially funded through a grant from the Getty Conservation Institute in cooperation with the National Park Service and administered by the Association for Preservation Technology. The study includes selectively cleaning and refinishing the monument without affecting the overall appearance. We would like the opportunity to present our research as a responsibility to the funders and the preservation community.

The Gateway Arch National Park was the first major national park development in the US after World War II and a turning point from the rustic to a more modern style of architecture. Its centerpiece, the 630 ft (192 m) tall Gateway Arch, is significant due to its architectural and engineering design and the role it played in the career of architect Eero Saarinen. The Gateway Arch was designated a National Historic Landmark in 1987 and retains a high degree of authenticity.

In 1947, Eero Saarinen entered the architectural design competition for the design of a monument. His winning entry was one of the first major designs Saarinen completed on his own and seen by some as his greatest contribution to American modern architecture. The design of the Gateway Arch is based on a weighted catenary. It is constructed of double-wall carbon steel and stainless steel triangular segments that reduce in size as they approach the apex. This stressed metal double skin carries the structural loads, eliminating the need for interior framing. The stainless steel panels are completely inter-welded and make up the exterior skin contributing to the overall character of the Arch. The reflectivity of the material is an important aspect of the Arch’s design, and the quality of the machined finishes adds to the overall character of the Arch.

Visitors can touch the monument where it meets the ground and experience its abstract simplicity close up. Consequently, there are body oils, perspiration and chemical pollutants from touching by hand, soiling collected on these residues, and graffiti either incised, etched or pounded into the stainless steel. The Gateway Arch has blemishes that were caused during fabrication and erection has also become soiled at unreachable heights.

The study focuses on cleaning and refinishing the stainless steel skin and avant garde measures studied to access the monument high above the ground.