What it is: Random droplets of paint on the surface; a defect or a technique
Spattering means individual paint droplets — larger than the fine mist of normal atomization — landing randomly on the surface. It can be an unwanted defect or a deliberate technique.
As a defect: Caused by partially dried paint in the nozzle breaking loose, too-thick paint, damaged needle tip, or starting a stroke with the trigger already pulled. Fix: thin paint more, clean the nozzle, start and end strokes off the surface.
As a deliberate technique: Spattering creates texture effects — rust, gravel, rock surfaces, skin pores, starfields, aged metal. To spatter intentionally: use slightly thicker paint than normal, reduce air pressure below optimal, and move close to the surface. You can also run a finger or tool across the needle to flick droplets.
Related: Atomization · Tip Dry · Viscosity