“International Orange” of the Golden Gate Bridge
The Golden Gate suspension bridge linking San Francisco to Marin Country (California) was built in seismic zone, therefore the increased steel strength and seismic retrofitting was strictly required. Steel was originally coated with a red lead primer to protect structural elements of the Bridge from corrosion during shipping. The architects decided to remain the red vermilion colour of the prime coating, because it complements the natural landscape harmonically and enhances the bridge’s visibility in fog.
However, the lead-based coating generates toxic emissions when exposed to precipitation. In 1990, the Golden Gate was repainted with acrylic paints of the similar colour (“International orange”). The engineers had to make a choice between environmental security and effective protective coating. The team consisted of 38 workers are permanently repainting the corrosion-damaged areas of structure nowadays. Despite this, every two years the coating quality is revised and, as a result, the engineers project the master plan to remedy the defects.