Painter's manuals and magazines wrote of "picking out" areas of a vehicle with line work. These thin lines set an aesthetic theme and created an energy, a vitality. Early fire apparatus was hand-made with small irregularities in the construction. The lines and stripes hid anomalies and gave the machine an air of precision. A crooked spoke stood out on a primed wheel. Once the decoration was done, the odd spoke wasn't noticed. Dots were often added to the lines to increase the energy and the sense of precision.
Stripes on a fire engine made it look lighter. Bulky parts are sliced into narrower areas of color. Gold leaf stripes light up and reveal the primary shape of the engine from far away. Up closer they can sometimes appear as voids or insubstantial, making the machine seem delicate. Wheel spokes and pump arms appear thin and graceful after stripes are added.
Most gold leaf stripes on fire engines were outlined in black. The contrast made the gold look more prominent and even brighter. The outline hid any rough edges in the gilding. It also made the gold appear to be a thick inlaid band of gold. The American painters were inspired by the ancient Greek and Roman art being excavated in Europe. Classical architecture and ceramics used these black "fillet outlines" wherever one color met another.