Here's Why The Golden Gate Bridge Is That Color

The story goes that when the painting crew finally reaches one end, they start all over again at the other. Paint superintendent Rocky Dellarocca in 2011 joked with a National Public Radio reporter that "yeah, you start at one end, and when you get to the other end, you retire." While the maintenance team of the Golden Gate Bridge is "continuously painting," said current superintendent Fred Mixon in an interview with KRON4, "it might not go one end to the other."

The constant maintenance is due to intense environmental factors. The bridge spans the Golden Gate Strait, which connects San Francisco Bay with the salty waters of the Pacific Ocean (via National Public Radio). Two auburns are continually pitted against one another: international orange versus rust red.

The salt-filled air is highly corrosive and causes extensive oxidation, the chemical process of rusting (via KRON4). Moist bay air weathers the bridge's steel, stripping electrons off the metal's iron atoms (via Sciencing). Add salt to the water and the chemistry catalyzes quickly. Salt water contains dissolved charged elements called ions. Their presence encourages the iron's electrons to be stripped away by oxygen atoms (via Sciencing). The rust flakes, and exposes fresh, unprimed steel ready for its own chemical degradation.

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