Spray Etch. An acid applied to a surface in a fine mist applied by a gun to lightly etch the surface. In the field of coin and medal manufacture spray etch is used more for cleaning than any other purpose. Strip stock and blanks can be spray etched in flow process. Blanks, for example, would be passed under a nozzle emitting the acid etching mist, then rinsed and tumble dried. While spray etch could be used in place other acid etching methods, they are seldom done so in the numismatic field.