Back around 1900, Tutt says, cars were basically motorized carriages and thus, painting methods were derived from the oil-based coating formulations used for traditional horse drawn carriages.
It was a complicated, expensive procedure to to apply the paint, and the drying time took several weeks. The color was luxurious, providing for brilliant paint jobs, but the paints couldn’t stand up to time and would end up turning yellow. There was no binding medium, Tutt says, so every time a color would fade or yellow, it’d have to be repainted. It gets expensive.
That long, expensive process is what prompted Ford to develop asphalt-based baked enamels for his cars — dark colors lasted longer, it fit in with the assembly line process and didn’t take as long to dry.
“This marked a big step for industrial mass production of the Model T and other low cost automobiles, since it synchronized the painting action to the frequency of the assembly line,” Tutt writes in her thesis.
In other words, this change in how cars were painted might seem simple now, but think about it this way — without these kinds of innovations, cars would’ve proven too expensive for most people and thus, a whole lot more of us might be on bikes.