Will go through color separation, screening and make-up made of the original (or original printing down), by Plate Text copied to the metal plates, made for the printing (or proofing) of the plate, is called proofing.
Plate burning is conducted in the plate. Will burn out original (glass plates or polyester film) covered in liquid metal has been coated photographic edition, by the exhaust vacuum, so original and close fitting metal plates, and visualization by light exposure, a series of chemical corrosion made of plate processing, which is the photographic plate a integral part of plate making, printing, the main connecting link between the process of printing (also including the camera, Revised Edition) product quality has a specific role.
To burn out of the process operation is concerned, it can be divided into Plate Surface treatment, coating photosensitive medium, exposure proofing and, layout chemical treatment, quality inspection, and several other key processes. The process after years of improvements in the development of the use of raw materials and process technology are constantly evolving with, the transition from cloudy to map protein version of concave gum version, polyvinyl alcohol (PVA) concave version of multi-metal version PS version And so on. The process conditions, briefly summarized as follows:
1, plate preparation Offset printing, from the pages of the printed repeatedly take the same print runs, because the layout has a stable wetting, namely: a blank page when printing part in absorbing, water; and graphic layout to absorb some of , transfer printing ink. For pages with a stable water absorption, must be used to plate (previously the most commonly used is zinc and aluminum skin leather, its thickness, usually 0.5 ~ 0.6 mm), surface treatment. Treatment methods should the nature of the plate, printing plate, and replication processes such as the case may be different, usually mechanical and chemical methods and so.
A. Mechanical graining method Type of graining with offset grinding machine, commonly known as "graining." The aim is to ground into a fine valley layout shape trachoma, plate surface area to expand the use of capillary effect, increase the absorption center for layout and graphic part of the blank part of the formation, layout and printing process of the water, the oil balance create favorable conditions. Graining collated before the first plate, and check whether the serious injury of layout, and then use petrol to the plate surface clear of oil, ink wash, followed by degreasing. Degreasing, zinc plate with sodium hydroxide (NaOH) or potassium hydroxide (KOH), aluminum nitrate used (HNO3) or sulfuric acid (H2SO4), can also be used sodium hydroxide (NaOH) or sodium chloride (NaCl) solution . Degreasing treatment is designed to prevent oil or ink contamination in the grinding process layout, resulting in printing layout from the dirty, also has the effect, you can shorten the graining time. After degreasing water rinse.
Then plate fixed to the Tang edition machine study the disk of the grinding plate to place two marbles, and then water moist, and add frosting, start grinding machine for grinding Edition version. As the impact and rolling marbles, will scrub the surface pressure to the friction plates, so that the surface of fine plates trachoma.
Will wear well plates were washed, and then deal with cleaning fluid to oxidation. After drying you can save the stand-by, saving should be stored in a dry place, the version of the base surface consistency, no friction between both sides.
More types of scrub, not a standard, commonly used are glass, sand, emery, etc.. Glass marbles marble grinding general, the steel marbles, ceramic marbles can also be used. Scrub particles, hardness, shape, texture of marble, size, weight, quantity and graining machine rotating speed, grinding time and other factors, determine the quality of trachoma.
B. Coarse wet sand blasting method
Surface treatment will be installed in cylinder plate, through the sand pump, water and sand mixture to breathe top disk rotating vane, the use of fast rotating centrifugal force of water and sand mixture sprayed into the metal surface to achieve the graining effect.