Silk-screen platemaking process (8)

b. Inspection and correction of monochrome screen adjustments.

(a) Examination of the vaginal picture.

a) Is the length of the tone appropriate? The monotone half tone image version requires a long time scale, a large contrast, a high light, and a dark tone.

The electrical separation process should be done in the full-length version, and check whether it is achieved: a very high light is not netted, the required height of the light part is 1%, the darkness needs the level of the part is 90 to 95%, the dark part can be 100%, Electron separation process can use a positive drawing method.

The gradation of the photographic direct-screening process should also be as high as possible. The shaded areas of the high-light part of the gradation should be 30 to 95%, the copying yang net should be 5 to 70%, and the darkness must be 100%.

b) The three levels of high, middle and low levels should be opened and enriched. Special attention is paid to the inspection of high-light levels, that is, it cannot be too flat, too deep, and it cannot be too sloppy or too shallow. If you are too peaceful and too dark, your high light will not rise. Too light and too shallow can cause high light levels and losses.

Correction of the Yin picture.

a) The focus should be on pulling away from extremely high light nets and high light levels requiring levels. If the high light tone is too high, then the corrosion layer is used to deepen and correct the parts of the required level. If the high tone is slightly flat, black ink is used to remove the parts that need to be netted.

b) The distance between the dark areas and dark areas of the required level is to be distanced, and the dark parts are generally corrected by etching.

c) Black and white dirty spots, scars and roads need to be clean, otherwise it will damage the appearance of the picture.

3. The production of color mesh adjustment. The color manuscript mainly expresses the object and the space by the change of color. The process principle of copying the color manuscript by silk screen printing is basically the same as other printing and copying principles, and they are all based on the tricolor vision theory. We have to understand and master the knowledge of light and color in order to carry out color reproduction of silk screen printing.

All the colors we see are due to differences in the absorption and reflection of light by various substances in nature. Without light, there is no color, and the color must be felt by human eyes.

Originals such as oil paintings, Chinese paintings, watercolours, natural color prints, natural color negatives, and color photos are all expressed in shades of different colors. Copying these originals faithfully with silk screen printing, unlike copying a line manuscript and monochromatic continuous manuscript manuscripts, only one printing plate is used, and generally three or more plates are required to be overprinted. Screen printing uses magenta, yellow, cyan, and black four-color printing, commonly known as red, yellow, blue, and black four-color printing. Therefore, when screen-printing and copying continuous color originals, it is necessary to make four-tone versions of magenta, yellow, cyan, and black in order to make a color halftone screen printing version.

The method for making the color mesh adjustment version includes indirect screening color separation method, direct screening color separation method and electronic color separation method. In order to better understand the principle of color separation, the following first briefly introduces the basic knowledge of color synthesis, the principle of color separation, and then introduces the production process of color mesh adjustment.

1 color light synthesis.

a. The three primary colors of light. When daylight (or a bundle of white light) passes through the prism, a bright color consisting of red, orange, yellow, green, cyan, blue, and violet colors is projected on the screen. This band is the visible spectrum, and the spectrum of visible white light is a continuous spectrum.

If the color light after decomposing through the prism is reconverged through the convex lens, white light can be displayed on the screen again. It can be seen that the white light is a complex color light formed by mixing various monochromatic lights.

The phenomenon in which polychromatic light is decomposed into monochromatic light is called dispersion. When the daylight (white light) dispersion is not sufficient, it can be found that the red, green and blue-violet light each occupy about one-third of the spectrum, while yellow, orange and cyan only occupy a very narrow part of the spectrum. Through experiments, people have found that some color light in the visible spectrum can be formed by mixing two other monochromatic lights in the spectrum, but red light and blue-violet light cannot be obtained by a hybrid method. Therefore, these two lights are called basic light colors. Chromatic mixing experiments tell people that green light in the middle of the spectrum can be mixed with red, blue and violet equivalent light energy (light energy) at both ends of the spectrum. If the red, green, and blue lights are mixed in unequal amounts, various colors in the natural world can be obtained. Therefore, the red, green, and blue-violet light colors are called the three primary colors of light.

The wavelengths of the three primary colors of light that are uniformly defined internationally are:

Red light: 700.0nm;

Green light: 546.7nm;

Blue violet light: 435.8nm.