SCREEN PRINTING-process

SCREEN PRINTING
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.