Gravity-fed airbrushes have the color cup positioned on top of the airbrush or
over the nozzle. The color cup is out of the way of your hand and does not
obstruct your view of the illustration. Gravity-fed airbrushes may use thicker
pigments. Less air pressure is required to disburse paint and the airbrush
clogs less often.
Figure 6-6 is an example of a gravity-fed airbrush.
Figure 6-6.A gravity-fed airbrush.
Siphon-fed airbrushes have side-mounted color cups or bottles and use air
passing through the airbrush to suck paint from the base of the color cup.
This is the most common type of airbrush system. Changing colors is as
easy as removing one color cup and replacing it with a color cup filled with
another color. The size of color cups or bottles varies.
Figure 6-7 is an example of a siphon-fed airbrush.
Figure 6-7.A siphon-fed airbrush.