The color cup is the small reservoir that holds paint for your airbrush. In gravity-feed airbrushes, it sits on top of the airbrush body and feeds paint downward by gravity. In siphon-feed models, a bottle attaches underneath and paint is drawn up by the venturi effect.
Cup sizes range from 1ml (tiny, for highly detailed work or very expensive paints) to 7ml or more (for larger coverage work). Most hobby and semi-pro airbrushes come with a 2–5ml cup, which is practical for most tasks.
Some airbrushes have a fixed, non-removable cup integrated into the body. Others accept interchangeable cups of different sizes — useful for switching between detail work and broader coverage without changing airbrushes.
Cleaning tip: Never let paint dry in the cup. Between uses, pour out excess paint, add a few drops of cleaner, and spray it through. For color changes, backflush before adding the next color.
Related: Gravity Feed · Siphon Feed · Backflush