Selection of originals and output of screen printing negatives

There are generally three types of commonly used manuscripts for screen printing: black-and-white line pattern originals, color continuous-tone originals, and color-printed originals (secondary originals).

Q: There are several kinds of line manuscripts? Can hand-drawings be replaced by computer drawings?
A: The black and white line pattern manuscripts generally have hand-drawn artwork and computer drawings. Hand-painted drafts have reflective drafts and transparencies, hand-drawn on white paper for writing, and text, graphics, tables, etc. written on carbon-sulfur paper using carbon black ink are transmitted texts. Density D = 3 or more, you can directly make screen printing.

Computer drawings are drawings, documents, forms, and other graphics drawn by various software. They are output on transparent film or sulfuric acid paper by a laser printer as a screen printing manuscript. At present, some factories use high-precision computer drawings in order to improve the printing quality.

Q: Why do we choose color reversal films for screen printing?
Answer: Continuous color manuscripts are:
1. The color reversal film is the most ideal transmission original in screen printing and copying. The image has high definition, bright colors, rich layers, and strong three-dimensional effect, and is suitable for high magnification. Density range D = 0.1 ~ 3.8, some can reach 4 or more. To scan the screen with a high-end scanner or electric extension, the image quality can be guaranteed. Magnification can be enlarged by more than ten times, suitable for large-format screen printing, and is ideal for large advertisements;
2. Color photographs are printed through color negatives and can be used as a reflection script. However, in the printing (copying), some levels of image loss, or due to improper operation will appear color imbalance, color cast, hue uneven, the density range of D = 0.1 to 2.6, dye particles rough, scanning with a flatbed scanner, image comparison Dirty magnification 4 to 7 times, and then enlarge the image distortion;
3. The color positive film is also copied from the color negative film. The image quality is the same as that of the color photograph. It is a transmission original document, and the density range is D=0.1~2.8. It is scanned with a flatbed scanner and placed at a magnification of 4~7 times.

Q: Why should color separations not be used for color separation?
A: This is because the surface of the color negative film has a layer of horseshoe (amber). When scanning, it can't find black and white fields, which is not good for calibration. The screen does not see the effect and it is not easy to grasp the color reproduction. The color of the image is the complementary color of the original scene, and the image is reversed. It is generally not used as a manuscript, but can be copied into a print or photo as a screen-printed manuscript.

Q: Why do you want to print the manuscript? Why can't I enlarge my copy?
A: The printed manuscript is also called the second manuscript. It is mostly a halftone reflection manuscript. It is a printed Y, M, C, K four-color printed matter. The density range is low, from 0.1 to 1.6, and some reach 1.8. rich. The use of the second manuscript to reproduce its density must be consistent, only the original copy, should not be amplified, or seriously distorted. The density of the print is lower than the scanner's density recognition ability. Scan with medium and low-grade scanners to prevent moiré from being generated in the copying of electricity. First, remove the textures and blur them. If there is no net function, you must stagger the angle of the screen. .

Q: When the output is negative, why do you use a laser image photosetter?
A: Inkjet printers, laser printers, and laser image imagesetters can all output transparencies for screen printing originals, but their density and image resolution (resolution) are different.
1. Inkjet printers can output transparencies, sulfuric acid paper. It prints out vividly colored document patterns and black-and-white documents with color inks, but the output film has a low density and poor quality. Can only be used for text printing negatives.
2. The laser printer can output transparencies and sulfuric acid paper. It adopts the principle of electrostatic imaging to make the toner adhere to the image area on the surface of the photoconductor to form an image. After heating, the toner is melted and fixed on the transparent substrate. The image is carbon. Powder particle composition, coarse particles, non-uniform layer, low image density, small dots missing large point deformation, layout trachoma, black dots, dirty version, can be used for pattern text color block screen printing manuscript, can not be used as color mesh tone manuscript Negative film.
3. The laser image-setter machine is a laser electronic color separation and screening system using a laser as a light source crystal modulator or a galvanometer system, and is controlled by a computer so that the laser passes or is prevented from being recorded to form an image on the exposed silver salt film. After development, high-precision dot silver salt film is obtained. Laser Phototypesetter output high resolution film, high density, dot, smooth lines, Jing Jing clear, rich layers, is the best screen halftone screen printing.

Q: Can I purchase a small laser imagesetter? What model is good?
A: High-grade printing is generally sent to the printing center's output outlet silver salt film. Small laser imagesetters on the market, such as Hangguang GP9002 and Linden 390 of Yingzhou, can output A3 silver salt film. From the technical parameters, they can meet the accuracy requirements of general screen printing business, and the price is about 20,000 yuan to 30,000 yuan. Printing plants can be equipped to use.



Source: Bison