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One important point was described above: Troubleshooting and promptly solving problems You must be familiar with various graphic defects. This skill can be slowly obtained from work experience. For example, hundreds of questions are observed and classified until they can be easily distinguished. Experts recommend documenting the process and adding it to the Troubleshooting table each time a problem is discovered and resolved. At the same time, attach a sample and, if possible, a photomicrograph. In order to facilitate learning and identify problems, this article will describe 24 questions in detail, with additional illustrations. Compare these descriptions with the ones you find and use them as a guide. (Note: All the illustrations are on the edge of the printed product. The direction is from top to bottom.) Image Edge Defects 1. Block edge Features: The edges of prints are irregular, some large gaps appear, and the graphics are smaller than expected. The main reason: Some of the edges of the graphic are permanently blocked by the following: a) Emulsion b) Dust c) Dry ink on the mesh Secondary Cause: The original itself or the screen fiber itself Causes Special Cause: Sometimes Poor ink transfer can also cause problems with edge clogging: a) Tension is too low and the image is too edged. b) The screen is separated from the substrate too soon. Note: These two examples are not fundamental issues with ink clogging. 2. Missing edge Features: Image edges are irregular, there are some bulges, the image is larger than expected. The main reason: Part of the edge of the stencil may be lost due to: a) the problem with the original b) the stencil or the block Note: Do not confuse it with the blemishes, because the edges are missing and appear in the same position on each print and cannot be inked or scrubbed. Method solution 3. Loss of detail (Less of details) Features: The thin lines and the edges of small images stick together, also known as resolution loss. The main reasons are as follows: a) The stretching tension is too small and the off-plan clearance is too large. b) The screen resolution does not meet the image resolution requirement. Secondary causes: Squeegee pressure is too high or the stencil is underexposed, causing the edges to be unclear. The third reason: a) The ink viscosity is too low for the ink absorption of the substrate. b) For high-resolution images, the surface of the substrate is too rough, textured, or uneven. 4. Sawtooth Features: Image has serrated or stepped edges. The first reason: Interference between mesh lines occurs in the following cases a) The production of the template is not very good (usually underexposed). b) The template is too thin to bend along the mesh line. c) The template is too thin for a given number of meshes. d) An undesired angle (1-10o or 80-89o) is formed between the edge of the image and the mesh line. Secondary causes: a) The viscosity of the ink is too high to flow through the mesh. b) The ink permanently blocks half or one quarter of the mesh. c) Sawtooth is a part of the original, for example, a low resolution laser printed image. 5. Dirt mark on the edge Features: There are disorganized points and lines on the edge of the image. The first reason: Some loose particles (dust, hair, lint, etc.) float in the work environment or on the substrate. Minor causes: loose particles on the original or dirt on the original. 6. Mesh-marks on the edge Features: The edge defects look like ghosts without being magnified, reducing image sharpness. After zooming in, it is a series of ideas (distributed on both sides of the edge). They are small squares. The first reason: The problem lies in the mesh, and some meshes are blocked by dry ink or emulsion. At the time of printing, some of the blocked holes opened up, while others did not change. So a checkered pattern appears. 7. Ink strings Features: There are many irregular long lines on the edges that look like lint and hair. The primary reason: ink viscosity is too high cohesion. (When the screen is separated, the ink is still connected together, leaving a part of the ink line.) Minor reason: the tension of the stretching net is too low, and the off-gauge gap is not suitable, so that the separation between the screen and the substrate is not good. 8. Static strings Characteristics: The phenomenon is similar to that of filthy dirt and ink. Under the microscope, it is a cross-extended line and a variable-size point. The separation between the screen and the substrate is not good. Sometimes it is very similar to ink, but it is usually more regular. The primary reason: insufficient humidity in the printing area (secondary reason: charge generated when the substrate is being dragged is not the same as frictional electrification.) Particular reason: Polyester-coated ITO substrate (both conductors and insulators) The charge is higher than other substrates, especially when it is dragged onto a metal plate. 9. Bleed, Bleeding Features: Bleeding is the phenomenon that the image area is enlarged due to the ink flow. It is not like the stains are produced during printing, but are formed after printing and are often formed during the drying of the ink.The bleeding is expanded in the same direction in all directions.Bleeding is different from the usual color spread, for example, textiles. The color of the material penetrates into the plastisol or the first printing ink diffuses into the second printing color.The primary reason is that the substrate is porous and the ink viscosity is too low. Due to insufficient drying, the pigment and solvent flow, or the drying temperature is too high. The reason is as follows: a) In the process of ink drying, the viscosity of the ink is reduced. b) The second ink is printed on the first ink before it has dried. 10. Double image Feature: It looks very similar to the eye with the naked eye, but when viewed with a microscope, it appears with a second edge that is parallel to the original edge. The first reason is that the tension of the stretch net is too small to contact the substrate before printing. Minor causes: a) When printing on an uneven, principled surface (eg, a circuit board), the ink that does not touch the substrate condenses on the edge of the stencil, and a second edge is printed. b) The freshly printed ink has not yet dried and is stuck by the template.