A rumor exists that the Golden Gate Bridge has a full-time paint crew that works year round. Urban legend has it that as soon as the painters are finished with the length of the bridge, they return once again to the beginning and repeat. They never cease in the application of the orange vermillion color for which the bridge is famous.
However, like the story of Sisyphus and his tedious task of rolling a boulder up the hill, the perpetual painting of the Golden Gate is only a myth. The truth is, the Golden Gate Bridge has undergone only 3 major repaints since its inception in 1937, with all other work done being only touch-up and routine maintenance. Given the Golden Gate’s in-situ environment of salt water, moisture and UV exposure, this is a remarkable feat of engineering and strategic maintenance. But how do they do it? For one, they understand the life cycle of paint.
Take a closer look
Heard the phrase, “About as much fun as watching paint dry?” But on the molecular level, there ‘s a lot going on inside paint that is actually fascinating. The atoms within paint are held together tightly by electron bonding making long chains of Carbon & Hydrogen. Oxygen & Nitrogen are also in the fold. These specific arrangements and structures give rise to things we call acrylic, alkyd and urethane.
Why coatings wear away
Atoms are being held together by a mutual need for electrons called bonding. The problem is electrons are fickle and are definitely not known for their loyalty. If the electron begins to feel a greater attraction to an adjacent atom or molecule, it will leave. Now we have begun a chemical change that cannot be undone – this is how things wear away. So as the electrons within paint begin to shift and bond to other molecules, fading begins. Electrons respond to energy. When energy is introduced into a chemical bond, the electrons get more excited – and now are less tightly bound to their constituent atoms. They can become more attracted to a new atom or molecule – this is why they leave.
How long do electrons stay?
Factors that determine the ultimate life cycle of a coating include:
- The amount of exposure it has to sunlight
- The temperature ranges it will experience
- The amount of moisture and rain the coating will endure
- The air quality of the coatings environment
- The chemical nature of the underlying substrate
These factors determine which paint products should be chosen according to location, and how often paint will need to be reapplied.