To prevent the ink from flowing through the screen except in the image area a stencil is applied to the screen fabric. There are numerous stencil systems on the market but the most popular is direct liquid emulsion. The stencil is created by pouring the emulsion into a specialized trough or 'coater' and gliding it along the mesh and depositing a thin film of this liquid on the fabric. When the liquid dries it is ready to be exposed.
Another way to create the stencil is to use 'capillary film'. This film is rolled onto a wet screen and once dry, is much like the liquid emulsion except that the thickness is more uniform and the shirt side of the stencil is much smoother. The uniformity and thickness achieved by use of 'cap' film can aid the reproduction of halftones and other resolution sensitive work but usually don't last as long as screens coated with liquid emulsion. There are other stencil techniques that are more complex but are generally not employed in the world of screen printed garments, such as indirect and direct-indirect.