The cause of the streak

I have always kept my squeegee used very sharply, but there are still streaks in the printing process. What causes this?

If you notice a streaking in the printing process, the first step is to sharpen your scraper again. In 50%-60% of cases, this step will solve the problem. However, the remaining 40%-50% is even worse.

If you have enough confidence in the correct hardness, proper sharpness, angle of installation, pressure and speed of the blade, but there are still streaks, you need to consider other aspects of treatment.

If the streaks are parallel, check if they appear in the same position on each printed page. If they are in the same position and you have ruled out a problem with a squeegee, then there may be problems with the panel. After unloading, replace with a new ink tray and continue printing. If it really is an issue with the ink board, the scar will disappear. If the streak still exists, then the reason is not on the ink board here.

The ink droplets from the squeegee during the process of paper inking are not the same in the position where the streak appears on each print sheet. Check if the ink is being transported in excess during printing. The ink droplets passing through the squeegee are printed. When the formation of streak. (This is a common problem in roller printing)

Ink/Material Problems Check the ink particles and the raised lines of the material surface (in the printed direction). If the ink does not contain large contaminant particles, the surface of the material is smooth and without any damage, the striations caused by these causes can also be excluded.

The problem of mesh fibers is that the edge of the ink sheet is not uniform, or the ink contains foreign particles, or the mesh is composed of uneven fine lines, which results in the destruction of the mesh fibers, and thus the occurrence of streaks. Check the presence of material fibers in the direction of the streak. The problems of fiber and build structure are easily observed with a microscope.

Problems with Coatings and Emulsions Coatings with meshed surfaces have uneven coating, the paint tank being used is too worn, or poor quality mixed emulsions may also cause uneven exposure due to exposure equipment problems.

The quality of the positive film is poor If the imagesetter is not clean or uses a laser printer to output the positive film, streaks may appear on the film. Later in the screening process, these scars were exposed on the screen and were not easily noticeable by the human eye until they were printed on paper. If halftone printing, this situation is even more obvious.

Sometimes, since the ink layer of the ink is too thin during printing, streaks may appear. We recommend using a squeegee with a hardness of 65-70 units to increase the ink deposition. But to avoid color ink or density range beyond the device parameters.



Source: Bison