A simple method and apparatus have proven useful for examining the quality of air-caps manufactured for paint spray guns. The technique combines accurate measurement of atomizing and fan air volumes, with velocity measurements taken through the axes of the flow pattern downstream of the cap. Initial comparisons of velocity profiles to actual spray patterns indicate that the profile symmetry (or lack of symmetry) correlates well with the resulting geometry of the spray pattern. This paper centers on the variation measured among supposedly identical air-caps. The conclusion proposes a standard method for specification of air-cap performance and manufacturing tolerances which would be beneficial to the finishing industry.