Flash or sheets of flash are terms used traditionally by tattoo artists describing the drawings of tattoo designs they used as "sales aids". These designs gave the potential customer a choice of the designs available. Historically traveling or itinerate tattoo artists carried "books of designs", where as those who worked in permanent locations used card or flat stock so they could mount their "flash" on walls.
Flash was drawn on everything from a good grade of water color paper, to the backs of advertising like wrestling, boxing and circus posters. The basic designs were outlined with a pen in an india ink, generally shaded with a method called "spit shading" to obtain a gradation from dark to light and finished with water colors. But the methods varied and the results differed greatly, from crude and primitive, to fine art.
Tattoo flash prices circa 1940's. Each design number on the flash corresponds to a set price.