Screen printing knowledge
1. How to divide the number of printed screens?
Regarding the screen number of the printing mesh, the international standard unit is 1T=2.5 mesh. 2.5 mesh equals one square inch and has 2.5 mesh holes. The mesh number indicates the density of the wire mesh. The higher the mesh number, the denser the wire mesh. The smaller the mesh.
The choice of mesh size can be selected according to the precision requirements of the printed products. The standard selected for the number of meshes is 70 to 200 mesh/in for a large amount of ink, 200 to 300 mesh/in for general printing, and 300 mesh/in or more for fine graphics.
2. The difference between screen printing and offset printing
Screen printing is a stencil printing process, which is called four printing methods together with lithography, gravure and embossing. The principle is that the printing plate transfers the ink through the holes of the stencil to the substrate to form images and characters by a certain pressure during printing. Features: a adaptability: can print on the substrate, curved surface, spherical surface, concave and convex substrate. b Ink layer thickness: strong stereoscopic effect, rich texture, ink layer thickness can generally reach about 30μm, and offset printing is 5-10μm. c light resistance, bright color.
Dry offset printing is a letterpress printing process: first transfer the ink on the printing plate to the rubber cloth roller, and then transfer the ink to the printed matter through the rubber cloth roller. Features: Suitable for cylindrical, conical and rectangular shaped containers, but non-cylindrical containers are difficult to print. Multi-color printing using offset printing on containers is more economical than screen printing, so it is widely used. Disadvantages: the printing gloss is poor, the edge of the graphic is not clear, and the printing plate dot is too small, the dot will penetrate into the rubber and the printed dot will be enlarged, and the printing effect is poor.
3. What should be paid attention to in screen printing?
The mesh number of the stencil; the actual width of the drawing line when drawing; pay attention to the graphics and the drawing surface in the stencil during printing, generally the distance from the four borders to the edge of the graphic is 10CM (convenient to scrape the squeegee); Be sure to choose a rubber sheet with a better texture, which is elastic, and the scraping surface (side) is straight and has no blisters. Immediately after printing, rinse off with water to prevent the ink from agglomerating and damaging the stencil. If ink is used, gently wipe the ink with a thinner such as ethylene or acetone, then wash it with water. Remember: Ensure that the stencil graphics are not blocked and can be used directly next time.