How to Prevent Vignetting When Using Screen Printing Mesh
Screen printing mesh plays an important role in printing. However, vignetting may appear when using screen printing mesh. In order to make good use of screen printing mesh, we need to know how vignetting is produced and how to prevent it.
A common phenomenon in the screen printing of vignette. The main form of expression is that the image portion on the screen printing plate after printing is not completely turned into a through hole at the edge portion after development, and a part of the mesh is still blocked by the photosensitive glue, and the edge of the image is not staggered. Qi, part of the graphic thin line is lost, the graphic size also changes. This reduces the quality of the print. There are two main reasons for vignetting. When using direct plate making, a white screen is used. The white screen has a reflection and scattering effect on the light source when printing, so that the photosensitive material at the edge of the image is not evenly sensitized, thereby causing vignetting: when the printing plate is not tightly attached to the screen printing, The photosensitive material at the edge of the image is exposed to light unevenness, which causes the appearance of vignetting.
How to prevent vignetting?
In order to prevent the appearance of vignetting and improve the quality of plate making and printing, the following measures can be taken.
1 Use colored screen to make plate making as much as possible without using white screen, but use red, yellow, orange and other colored screens to make plates, use the color of the screen itself to absorb the light from the source, and reduce the reflection of the screen light when printing. , scattering phenomenon, to achieve the purpose of preventing vignette.
2 Pre-coating vignette prevention liquid method Pre-coating vignette prevention liquid is a solution which is made of ethanol and cresol and ethanol-soluble red dye, and is blended according to a certain ratio. Before coating this solution, the screen must be cleaned and dried, then the shading prevention solution is applied and dried immediately. After drying, the photoresist can be coated and printed, so as to prevent the appearance of vignetting. .
3 When using screen printing mesh for printing, pay attention to the plate negative and the screen printing plate to be compact and close to ensure that the photosensitive material receives light evenly, to achieve the effect of preventing the appearance of vignetting.