The range of applications for screen printing is very wide and any kind of object other than water and air (including other liquids and gases) can be used as a substrate, including paper, plastic, metal, pottery and glass. Screen printing is made up of five main elements: the screen printing plate, the printing squeegee, the ink, the printing table and the substrate.
Transcription printing is the simplest form of perforated printing and began in the late 19th century. In this type of printing, a wax paper graphic plate is made on special wax paper by means of a typewriter or an iron pen, on which the wax paper plate is printed with an ink roller, and the desired printing effect is obtained on the substrate. The most widely used of the perforated plates is screen printing.
Screen printing is the silk fabric, synthetic fabric or metal screen taut on the screen frame, the use of hand engraved lacquer film or photochemical plate making methods to produce screen printing plates. Modern screen printing techniques, on the other hand, use photographic materials to produce a screen plate by photographic plate making (so that the screen holes in the graphic part of the plate are through-holes and the non-graphic part of the screen holes are blocked).
The basic principle of screen printing is that the graphic part of the screen plate is permeable to ink and the non-graphic part is impermeable to ink. When printing, ink is poured into one end of the screen printing plate, and a screen printing squeegee is used to apply a certain amount of pressure to the ink part of the screen printing plate, while moving towards the other end of the screen printing plate. The ink is squeezed into the substrate by the squeegee from the mesh of the graphic part during the movement. Due to the viscous effect of the ink and the print fixation within a certain range, the printing process is always in line contact with the screen printing plate and substrate, the contact line with the scraper to move and move, as the screen printing plate and substrate to maintain a certain gap between the screen printing plate through its own tension and produce a reaction force on the scraper, the reaction force is called rebound force.
Due to the role of rebound force, so that the screen printing plate and the substrate is only moving line contact, while the other parts of the screen printing plate and the substrate for the disengagement state. So that the ink and screen fracture movement, to ensure the printing size accuracy and avoid rubbing dirty substrate. When the squeegee is lifted after scraping the entire page, the screen plate is also lifted and the ink is lightly scraped back to its initial position. This is a printing stroke.
The four main parameters of screen printing are the mesh size of the screen, the angle of the screen, the tension of the screen and the thickness of the emulsion.