Screen Printing
Screen printing refers to the use of a mesh screen as a printing plate, which is made into a screen printing plate with images through photosensitive plate making methods. Screen printing consists of five main elements: the screen printing plate, squeegee, ink, printing table, and substrate. The basic principle of screen printing is that ink can pass through the mesh holes of the image part of the screen printing plate, while the non-image part cannot. During printing, ink is poured onto one end of the screen printing plate, and a squeegee is used to apply pressure to the inked areas of the screen printing plate while moving evenly towards the other end of the screen printing plate. The ink is squeezed from the mesh holes of the image part onto the substrate as the squeegee moves.
Stencil printing is the simplest form of perforated plate printing and originated in the late 19th century. This type of printing is done on special wax paper, which is then typed or written on with an iron pen to create a wax paper stencil. Ink is then rolled onto the wax paper stencil, resulting in the desired printing effect on the substrate. Among perforated plate printing methods, screen printing is the most widely used.
Screen printing involves stretching fabric, synthetic fiber fabric, or metal mesh on a frame and making a screen printing plate using hand-cut lacquer film or photosensitive plate making methods. Modern screen printing technology utilizes photosensitive materials to create screen printing plates through photolithography methods, where the mesh holes in the image part of the screen printing plate are open, while the mesh holes in the non-image part are blocked. Screen printing is used for various applications such as painting, printmaking, posters, business cards, book covers, product packaging, labels, textile printing, glass, metal, and other flat substrates.
Direct plate making method: The direct plate making method involves first placing a photosensitive film with the photosensitive side facing up on a workbench, placing a stretched mesh frame on the film, pouring photosensitive emulsion into the mesh frame, and using a soft squeegee to evenly coat the mesh frame with pressure. After thorough drying, the plastic film base is removed, leaving the photosensitive film-coated screen ready for exposure. After exposure and development, a screen printing plate is created.
Process flow: Screen stretching - degreasing - drying - peeling off the film base - exposure - development - drying - plate repairing - mesh sealing
Indirect plate making method: In the indirect plate making method, the indirect film is first exposed, hardened with 1.2% H2O2, and then developed with warm water. After drying, a peelable graphic film is made, which is then placed on the stretched screen mesh, squeezed tightly to the wet screen mesh, and the film base is removed. After drying with air, a screen printing plate is produced.
Screen printing originated in China more than two thousand years ago. Even in ancient times, methods such as paste-resistant printing appeared during the Qin and Han dynasties. By the Eastern Han Dynasty, paste-resistant wax dyeing methods were widespread, and the quality of printed products improved. By the Sui Dynasty, people began using frames with stretched silk nets for printing, evolving from paste-resistant printing to screen printing. According to historical records, exquisite clothing worn in the Tang Dynasty's palace was printed using this method. By the Song Dynasty, screen printing continued to develop, and improvements were made to the originally used oil-based paints by adding starch-based gums to dyes, enabling screen printing to produce more vibrant colors.
Screen printing consists of five main elements: screen printing plate, squeegee, ink, printing table, and substrate. The basic principle of screen printing is that ink can pass through the mesh holes of the image part of the screen printing plate, while the non-image part cannot. During printing, ink is poured onto one end of the screen printing plate, pressure is applied to the inked areas of the screen printing plate with a squeegee, and the ink is squeezed from the mesh holes of the image part onto the substrate as the squeegee moves towards the other end of the screen printing plate. Due to the viscosity of the ink, the print adheres within a certain range. Throughout the printing process, the squeegee maintains continuous line contact with the screen printing plate and the substrate, with the contact line moving with the squeegee. The tension of the screen printing plate itself generates a reactive force against the squeegee, called rebound force. As a result of the rebound force, the screen printing plate and the substrate only have linear contact during printing, while other parts of the screen printing plate are separated from the substrate. This allows the ink to break away from the screen printing plate during printing, ensuring printing dimensional accuracy and avoiding smudging on the substrate. After the squeegee passes over the entire surface, it is lifted, and the screen printing plate is lifted, lightly scraping the ink back to its initial position. This completes one printing cycle.