A thing of beauty may indeed be a joy forever, as long as it is properly protected.
Architectural preservationists are finding that advances in construction materials and techniques are not only helping to reclaim the splendor of historic landmarks, but they are also ensuring improved functionality for future generations.
"Preservationists know that by saving historic buildings and landmarks, they are honoring the past, enriching the present, and protecting the future," said Bob Hansen, global industry executive director for construction and Dow Corning president of Europe. To fully safeguard the world's historic, artistic, and architectural heritage, the first priority of any preservation effort is to protect the structure from the elements, according to Hansen.
"Construction weatherproofing and glazing sealants may represent a small portion of the overall preservation costs, but it can save substantial energy costs and prevent interior damage from water leakage," Hansen said. "We're developing innovative products and techniques that bring the past into a functional future."
Preservation architects are increasingly turning to silicon-based products, due to their superior resistance to sunlight, ozone, rain, snow or temperature extremes. Under normal conditions, silicone sealants can provide 20 years or more of leak-free service in exterior building applications, compared to the lifespan of five to seven years for some commonly used organic urethane sealants. As an example, silicone sealants and coatings maintain long term adhesion to concrete, masonry, stone, and exterior insulation and finish systems, as well as glass and metal substrates. They are easy to apply over a wide temperature range, can be applied in hot or cold temperature extremes, which allows for year round application outdoors.
Silicone sealants provide superior performing technology due to their chemistry; they will not crack, split, or tear. They stay flexible and maintain adhesion, even while being stretched or compressed, which is a basic requirement for any properly designed joint.
Restoring, renovating and adapting historic buildings and landmarks to current and future needs present challenges for workers who must maintain the underlying structure of these buildings. The use of silicone products provides a long term solution by preventing water, air, and contaminants from entering the structure. Failure to properly seal structures can result in premature life, internal damage, and deteriorated aesthetics.
"Whenever we work on a landmark project, we pay close attention that the materials not only perform well, but they complement the aesthetics and character of the building," said Hansen.
Examples of landmarks that have benefited from modern preservation techniques and products include:
- Washington National Cathedral - The sixth-largest cathedral in the world and second-largest in the United States, Washington National Cathedral is a solid masonry structure built from high-grade limestone blocks that average 300 pounds. Because construction took 83 years, parts of the cathedral were already being renovated even before construction was completed in 1990. As part of the ongoing renovation/preservation efforts, deteriorating mortar is replaced with silicone sealants from Dow Corning.
- Mount Rushmore - For nearly its first 50 years, Mount Rushmore received annual facelifts from maintenance personnel who filled cracks of varying sizes with a patching compound of granite dust, white lead, and linseed oil. But because the cracks returned as soon as the linseed oil dried out, the National Park Service switched to high performance Dow Corning silicone sealants in the early 1990s. This was in part due to their long-lasting performance, watertight bond to granite joints, as well as its ease of application in temperature extremes.
- Statue of Liberty - After enduring punishing, wind-driven salt water for 100 years the penny-thin copper-skinned Statue of Liberty was not only showing its age, but it was leaking. To restore the landmark and prepare it for future generations, historical architects selected Dow Corning silicone sealants for its superior adhesion capabilities to copper, flexibility in extreme weather conditions, long life, and compatibility with residual coal tar -- the original sealant used when the statue was erected in 1886.
- Guggenheim Museum - Opened in 1997, the Guggenheim Museum in Bilboa, Spain, has been hailed as one of the most significant architectural designs of the 20th century. With free flowing lines and form standing in stark contrast to surrounding low-lying art deco buildings, the museum has an exterior formed from a blend of titanium, limestone and glass. Due to the exposed position of the building, and the potential deterioration of the construction materials and their bonding system, and to minimize the possibility of "streaking" and disruption of the flow pattern of the museum's skin, Dow Corning consultants recommended natural stone and facade silicone sealants to help it withstand structural movement, offer protective qualities, and provide a long term weather-sealing solution.
- The Brussels Berlaymont building - One of the major symbols of the European Union, the Brussels Berlaymont building reopened after almost 10 years of renovation. The building retains the original structure but is enhanced by a blanket of high-tech facade made of 21,000 glass louvers, which provide energy conservation as well as weather protection. Structurally adhered with Dow Corning sealant, the louvers are controlled by a computer connected to weather system sensors and move according to sun radiation, temperature, wind and shadow.