To eliminate the softness and obtain a hard, sharp-focused edge, you must spray through a stencil—commonly called a frisket in airbrush illustration, but a stencil in T-shirt painting—or around an object. In this way you block the overspray and create the edge of a shape. Frisket film, a thin sheet of self-adhering plastic, is the material used to make the frisket. It is self-adhering and is used to cover a contour line drawing. The airbrusher cuts through the frisket film with a stencil knife to open up areas that are to be sprayed. Note that when airbrushing on T-shirts or fabric, acetate stencils should be used.

Some recommendations follow:

—When you peel off the protective backing to expose the frisket film, save the backing paper and use it to hold cut pieces of frisket for reuse. After removing the backing from the frisket, lay it over your line drawing and rub the air bubbles out to the perimeter.

—Don't press down hard on the frisket film or it may be difficult to remove.

—Cut with a sharp blade. Practice scoring the film without cutting into your paper, and change blades often.

—Don't leave frisket film on your work for long periods of time (24 hours or more) or it may become permanently adhered.

—After you have practiced cutting frisket, spray around the edges to see how it works. Move the cut shapes around the page to create a small abstract painting.