Four-color screen printing process points (in)

The main goal of half-tone screen printing is to control the ink deposition, so that the amount of printing ink is extremely accurate, and people seem to feel that the brightness, darkness, and subtle levels of the image colors can faithfully reproduce the originals. In the operation, this effect must always be consistent between the printed sheet and the printed sheet, and any change in the process will cause differences in the color and level of the image, and the variable factors must be strictly controlled throughout the process. Only print qualified products. However, to control the entire process, the original must first be controlled and selected. The original is the basis.

Originals are provided by customers, and some are also called originals. Strictly speaking, only original works can be called originals, while a Chinese painting is original. Color reversal films taken with originals, black and white or color photos cannot be called originals but are called manuscripts.

The form, color, and structure of the manuscript are very different and can be clearly categorized.

1. Divided by type of original

(1) Photographic originals - color reversal film (natural color film), color copy positive film (color positive film copied with color negative film), color photos, and black-and-white photos.

(2) Original artwork - Chinese painting, gouache, watercolors, prints, and pencil drawings.

(3) The second manuscript—generally refers to a color reversal film or color photo that is a copy of an original artwork.

(4) Printed manuscripts—refers to the use of prints as manuscripts.

(5) Line manuscript—refers to black-and-white line drawings and manuscripts consisting of patterned fields, art characters, and text.

2. Divided by light

It can be divided into two categories: transmissive and reflective.

(1) Transparency. The original is transparent. When the color is separated, the light source shines on the back of the original and the transmitted light is used for color separation.

(2) Reflection draft. In color separation, the light source illuminates the front surface of the original and is a manuscript that uses the reflected light of the original for color separation. Reflections include original paintings, color photos, black-and-white photos, and prints.

The quality of direct color separation is best with the original. This type of manuscript has a small contrast, generally only about 1.4, and the brightness density is 0.1, 0.3. Shadow density 1.5-1.7.

Color photographic paper is a kind of color multi-layer photosensitive material, and its structure and coloring principle are similar to those of reversal film. The color photo image is enlarged and printed on the color photo paper by the color negative film, so the light and dark contrast is intense and the color is vivid and real. Only because of the reflection of the original, but not contrasting contrast of the reversal film, but also because it is a color negative film copy or amplified, so the level of loss, the color has color cast, it is appropriate for the original large or reduced copy.

3. Applicable and non-applicable

The manuscript is the basis of screen printing and copying. The quality of the manuscript is directly related to the quality of the plate making and printing products. Therefore, when the manuscripts and process design are to be carried out, the manuscript submitted by the customer must first be carefully examined and confirmed to determine whether the screen printing process is suitable. Platemaking requirements.

4. Suitable for screen printing manuscripts

Applicable manuscripts are often referred to as qualified manuscripts, that is, in accordance with the requirements of the screen printing process for making a master plate, and it is not necessary to make a manuscript that can be copied by processing correction. The standards are: 1 image, good resolution; 2 fine particles, clean and clean the map; 3 moderate contrast, high and low-key levels rich; 4 hue is correct, colorful, sense of color balance; 5 copy, the magnification does not exceed 3-4 times; 6 originals such as reflections and drawings should be flat and free from damage and dirt.

(to be continued)