A silk-screened T-shirt.
Common problems arise in silk screen printing. You can troubleshoot each problem with the proper solution as they come up. Silk screening printers come in a variety of formats and configurations. Every silk screening machine will have wood or metal frames stretched with taut mesh. The mesh is imaged with a design. Ink is forced through the mesh with a squeegee to print an image. Here are solutions to common silk screening problems.
Instructions
1. Graphics for silk screen printing are first printed as a film positive. To make a film positive, print a graphic from a computer on a piece of clear vellum paper. The image must be very opaque to make a successful silk screen. If it is not opaque, flip it over and go over the design with black ink until it is opaque. The film positive is placed over a silk screen coated with photo emulsion, and exposed to a bright light. The image is developed on the silk screen with a spray of warm water.
2. The silk screen frame must be properly imaged for successful screen printing. If ink will not print through your silk screen frame, it could be overexposed, with emulsion stuck in the image area. Try a shorter exposure time. If too much photo emulsion comes off while developing your image on the screen, it is underexposed. Try again with a longer exposure time.
3. Silk screen printing ink must be at the proper consistency for successful results. If the ink is too thick, it will not print through the screen mesh. Thin the ink and try again. Use the proper thinner for the ink, adding a little bit at a time and testing. Water-based inks thin with water, while plastisol T-shirt ink thins with mineral spirits. If the ink is too thin, it will smear on the printed surface.
4. Use the proper mesh count for the material you are printing on, and the ink you are using. Most ink manufacturers recommend a mesh count for their inks. Opaque white plastisol ink is printed through mesh counts from 80 to 120. Black water base or plastisol ink is printed through mesh counts from 120 to 180. Plastisol process color inks are printed through mesh counts from 305 to 355.
5. Ghost images appear as a doubling of the printed image next it, when the screen tension is too slack. Make a new screen with the image on a properly tensioned silk screen. Ghost images can also appear on T-shirts between prints in multiple color printing if the T-shirt comes off the shirt board between colors. Use an adequate amount of spray glue to keep the T-shirt on the shirt board between impressions to solve this problem.
