Silkscreen Printing

Silkscreen printing, or serigraphy as it is known in America, has its origins in japanese stencilling, but the screen printing process that we know today probably stems from the patents taken out by Samuel Simon of Manchester at the turn of the century. He used silk stretched on frames to support hand painted stencils, a process also used by William Morris. During the First World War in America screen printing took off as an industrial printing process especially for 'point of sale' advertising in the chain stores.

Around this time the invention of the photographic stencil revolutionised the process. In the following years improvements were made in the presses, inks and chemicals used, but apart from the introduction of computer technology in the 1980's very little else has changed since. Artists have also used silk screen printing, especially since the days of pop art in the sixties - Andy Warhol, Rauschenberg and Hamilton are a few notorious examples.

The equivalent of the printing plate for the screen printer is the screen - a wooden or aluminium frame with a fine nylon mesh stretched over it. The mesh is coated with a light sensitive emulsion or film, which - when dry - will block the holes in the mesh. The image that needs to be printed is output to film either by camera or image-setter. This film positive and the mesh on the screen are sandwiched together and exposed to ultra-violet light in a device called a print-down frame. The screen is then washed with a jet of water which washes away all the light sensitive emulsion that has not been hardened by the ultra-violet light. This leaves you with an open stencil which corresponds exactly to the image that was supplied on the film. Now the screen is fitted on the press and is hinged so it can be raised and lowered. The substrate to be printed is placed in position under the screen and ink is placed on the top side of the screen, (the frame acts also as wall to contain the ink ). A rubber blade gripped in a wooden or metal handle called a squeegee (not unlike a giant wind-screen wiper) is pulled across the top of the screen; it pushes the ink through the mesh onto the surface of the substrate you are printing. To repeat the process the squeegee floods the screen again with a return stroke before printing the next impression.