Effect of Screen Color on Printing Effect

The colors of the screen are white, yellow, amber, red, and so on. There are still many people who do not realize the limitations of white screens. White screens have obvious flaws in restoring fine lines and layers of originals. Sometimes, despite the relatively thick coating process, they cannot completely eliminate the sawtooth edges. The phenomenon is caused by the inherent scattering phenomenon of white screens. That is, the phenomenon of "back sun".

The so-called "back sun" means that when light reaches the emulsion layer through the transparent part of the film, reflection, refraction, and slow shot occur on the surface of the white screen at the middle or bottom of the coating layer, just from the coated surface. The bottom and inside exposure. It can cause halo when exposed, affecting the reproduction of tones.

So why should we choose the color of the screen?

It turns out that yellow screens are preferred in many colors. Why use a yellow silk screen? We know that the splendid color of the natural world is due to the effect of light. Without light, there is no color. The color of light is determined by the frequency of light waves. Red, orange, yellow, green, cyan, blue, and purple are the light that the human visual nerve can feel and become visible light. The surface of the object absorbs light selectively and reflects it to get different colors. In short, any color we can see is the color of light. That is, when a beam of light strikes the surface of a yellow object, only the yellow light is reflected, irritating our visual nerves and coloring, while other colored lights are absorbed, so we see that the color of the object is yellow.

Since the screen printing uses ultraviolet light during the exposure of the printing plate, the purple light is reflected by the mixture of the two hue of cyan and magenta in the color, that is, the yellow hue is absent in the black light. At the time of exposure, the yellow of the purple screen mesh is superimposed on black, so the surface of the yellow screen (ie, the bottom of the emulsion layer) is not sensitive or less exposed, so that the phenomenon of “back exposure” does not occur and the resulting image has high definition. . Does not produce vignetting.


Source: "International silk screen"