Analysis of the hottest dot shape III

Point shape analysis (III)

6 Special shape points. From the perspective of technology, changing and selecting different point shapes is the need of printability. However, in order to meet the needs of art reproduction, advertising and special interests, special shaped dots (or artistic lines) are often used to increase the artistic atmosphere of the picture and obtain specific artistic effects. Commonly used artistic patterns include concentric circles, horizontal waves, vertical line stripes, cross gauze patterns, gauze patterns and brick wall patterns. Different dot shapes have different effects on the dot gain in the printing process. The conclusion obtained from the experiment is that the best point shape should be a regular chain structure, with circular points in the highlight and dark parts and oval points in the middle part

the following figures are the effect diagrams of diamond plus, linear plus and cross plus respectively. (for the convenience of observation, 30 line/inch extensometers or strain gauges are used to display the elongation of the standard tensile samples (all made by Photoshop), which provides a guarantee for the water safety of Dunhuang, and the actual printing effect is much better). We can easily find the different effects expressed in the three pictures

through the introduction of different points above, we learned that one is pressure. When selecting points for different products, we should also consider the performance ability of the point shape for different products. For example, the sense of hierarchy of square points is much stronger than chain points. In the selection of points with special shapes, don't choose blindly. The first thing to consider is what shape of points is more effective for the theme of printing, and whether this selection is really necessary. For example, if the working voltage of the chain point is 5V, it has the characteristics of excessive softness in the middle tone, so the chain point can be selected on many prints with rich middle tones (especially people); Water wave point has the unique movement of water wave, which is often used in special situations such as water sports; Similar performances include concentric dots on vortices, brick dots on buildings, broken line dots on speeding cars, single line dots on bamboo forests, etc

the selection of points with different shapes mentioned above is of great significance for the production of lithography

it is also the choice of point shape, which is not so rich for gravure printing (especially engraving gravure). Due to the limitation of engraving technology (now mainly the limitation of engraving knife), the point shape used in gravure printing is often very simple, mostly rectangular and diamond. But for gravure printing, the change of dot shape has a new role

different from the flat plate, the dot shapes of various color groups on the gravure printing plate (plate cylinder) are often different. Generally, the yellow and black plates adopt almost square points, the cyan adopts longitudinally stretched diamond points, and the magenta plate adopts horizontally stretched diamond points (the above is considered relative to their respective line angles). With this change of point shape, gravure printing can more effectively avoid moire stripes on the print due to insufficient point angle difference (there are only three kinds of point angles for engraving gravure printing: 45, 30, 60)

similarly, different from lithography, gravure printing seldom considers the problem of dot increase in the printing process, but will more consider the problem of ink transfer rate (ink output rate in the hole). During the experiment, people found that the closer to the circular dot, the greater the amount of ink transferred in the printing process. Based on this, in the development process of gravure printing, hexagonal dots continue to appear, And octagonal points (due to the limitation of the carving knife, it is almost impossible to produce circular points on the gravure plate cylinder)

the above article has made some introductions to the characteristics and functions of different shapes of points, hoping to be of some help to readers in future work

Author: Xu Lina

art source: must win