Screen printing, sometimes referred to in popular culture as silk screening, is a popular method of applying images to substrates (materials that are printed on). The most well-known use of this process is the production of images on T-shirts. It's a relatively simple technique and can be performed at home. The basic process is to take mesh (typically wire) that is stretched over a frame and create a stencil on it. The stenciled area remains open mesh, while the non-stenciled area is filled or overlaid with a non-porous material. The mesh is laid over the substrate and filled with ink. A squeegee is pulled across the mesh to force the ink through the open area of the mesh onto the substrate,creating the image. This process is universal to all types of screen printing. Even rotary screen printing uses this process, though the mesh is fixed to a cylinder and the squeegee resides inside the cylinder. The primary differences in screen printing are found in the types of ink used and the effects they render.
One of the most common inks used in screen printing, plastisol is a suspension of PVC particles in what is referred to as a plasticizer--a chemical additive that increases flexibility. This is used in the production of garments, and though it gives good image clarity, it has a very plastic feel and appearance.
Discharge inks work by affecting the existing dyes in a garment, usually to lighten them.
Flocking is a process in which glue is applied to create the image, then a foil is applied to create a shiny appearance to the design.
Water-based inks offer more penetration of fabric than plastisol-based processes and are employed when a softer result is sought.
Although textile applications are very common, screen printing can also be employed on circuit boards, wood, glass and even metal.