What it means: Air and paint mix outside the airbrush body
In an external mix airbrush, compressed air and paint meet and mix in front of the nozzle, outside the airbrush body. The paint is pushed out by a separate air stream that surrounds it, breaking it into droplets at the point of exit.
External mix airbrushes are simpler in design, easier to clean, and less prone to clogging — making them a reasonable choice for beginners or for heavy, thick paints (fabric paint, ceramic paint) that would block an internal mix design.
Limitation: External mix produces a coarser, less refined spray pattern compared to internal mix. Fine detail work is difficult to achieve. Most serious artists use internal mix airbrushes exclusively.
Vs. internal mix: In internal mix, air and paint combine inside the airbrush body before exiting, producing a much finer, more consistent atomization.
Related: Internal Mix · Atomization · Single-Action