The silk screen process is a stencil technique which offers the amateur an easy method of making prints, greeting cards, posters, book covers and many other printed objects. It may be done on wood, cardboard, cloth, paper, metal, or celluloid in one or more colors. The set-up is simple. A wooden frame is used on which is stretched a piece of stencil silk or organdy. This frame is hinged to a baseboard with two pin hinges so that it may be detached with east (fig. 177). The silk screen is blocked out except for the area of the design. Printing is done by forcing paint through the open mesh of this area with a rubber squeegee.
The frame for work of average size is made from 11/4-inch square white pine. Its dimensions should be about 2 inches wider and 6 inches longer than the design. There are two types of frames which differ only in their provisions for stretching the silk. In the first the frame members are mitered and grooved (fig. 178). The silk is fitted to the frame by tacking it loosely in place along the outside edges of the frame. Then, four 1/2-inch square cleat sticks are pushed into the grooves, over the silk, stretching the silk drum-tight (fig. 179). The second type eliminates the use of grooves and cleat sticks. In this case the frame is plain with mitered corners. The silk is placed over the frame and tacked evenly in place along one side. Next, the loose edge of the silk directly opposite the tacked portion is stretched tight and fastened with one tack in the center of the frame edge. To stretch the silk evenly, it is pulled taut and tacks are inserted alternately on each side of the center one. After the two sides are finished the same procedure is applied to the ends of the frame, tacking alternately from the center until the silk is stretched smoothly and tightly over the entire frame. The surplus fabric at the corners is folded and tacked to complete the process. The screen is now ready for the design.
One of the simplest means of applying a design on the screen is the paper mask or stencil method. The picture or lettering to be reproduced must be drawn full size (fig. 180). Next a plain sheet of tracing paper, large enough to cover the screen, is coated with shellac (fig. 181). While this is drying the design is coated with wax. The thin film necessary may be rubbed on with the fingers (fig. 182). A good wax for the purpose can be made from equal parts of beeswax, kerosene, and linseed oil. The tracing paper, shellacked side up, is now placed over the waxed drawing. Run a roller over both until they adhere (fig. 183). Then, with the wax coating holding the design in place, all parts of the design that are to print are cut out of the tracing paper with a razor blade or stencil knife and stripped away (fig. 184). After completing the cutting, place the silk screen over the design and use a thin, soft pressing cloth and a medium hot iron to attach the design to the screen (fig. 185). Peel off the drawing from the bottom of the stencil, line the edges of the screen with masking tape to prevent the paint from leaking through and the screen is ready for use (fig. 186).
Now that the screen is completely blocked off except for the area to be printed, place a piece of paper beneath the screen, pour in a quantity of paint, and wipe it from one end of the frame to the other with the rubber squeegee (fig. 187). A variety of paints are made specifically for silk screen use and may be obtained at art supply stores. They come in a heavy paste-like consistency and for best results should be mixed with one or more of the Special media provided for this purpose. The commonest are the transparent base, extender base, retarder, and reducer; experience will soon teach you the best to use for various types of work. The illustration shows the screen in a raised position with the work in place (fig. 188).
When you have printed as many copies as desired in this manner, the screen should be cleaned with turpentine or kerosene to remove the paint, and with alcohol to dissolve the shellac which holds the stencil. In both operations, place several thicknesses of newspaper under the screen to absorb the cleaning agent. As each sheet becomes saturated discard it, leaving a fresh one exposed.
A variation of the paper stencil method described above calls for the use of a prepared film made specifically for silk screen work. The film takes the place of the shellacked paper; it is easy to handle and yields more professional results.
One side of this film is covered with waxed paper, and the drawing should be taped securely to this side. The design is cut out with a knife, as above, care being taken not to cut through the waxed paper which holds the "islands" in place. When the parts of the design which are to print have been stripped away the film is attached to the screen in the following manner. Place the screen on top of the film and wet a small portion of it with lacquer thinner. As soon as the dampened area begins to darken, remove any surplus with a dry rag, rubbing and pressing vigorously. Since the film has a thin coating of lacquer on it, it adheres to the silk as soon as the thinner renders it tacky. Continue this operation until all parts of the film have been covered, strip off the drawing and the waxed paper, tape the edges and print in the manner described above. When cleaning, use kerosene to remove the paint and lacquer thinner to dissolve the stencil.