There are many noteworthy details in the prepress design process of flexible packaging. Here we will focus on the following points for attention.
1. Small words and lines
(1) Small text and lines should be designed to be monochromatic to avoid multicolor overprint.
(2) The width of thin lines should not be less than 0.1 mm, otherwise it is easy to be lost or unclear in printing.
(3) The net height of Chinese font shall not be less than 1.8mm, and that of English font shall not be less than 1.5mm.
(4) Special attention should be paid to the design of anti white text. If the text is small, especially when the stroke is thin, monochrome should be used. We should also pay attention to the selection of fonts, such as round head, bold, etc., are the better choice, while song style, old song style (horizontal thin vertical thick) and other fonts with too big difference should be used with caution. If this type of font is used in the design, the net height of Chinese font should not be less than 2.5mm, and the net height of English font should not be less than 2mm.
2. Transition network
(1) If you want to print anti white text on the transition screen, the transition screen should be designed as spot color to avoid overprint inaccuracy.
(2) When the dot area ratio of the transition network is less than 30%, use the reversed word carefully.
(3) When the dot area ratio reaches 70% ～ 85%, it is difficult to get a smooth and bright transition effect when the transition net is designed with some colors (such as black, dark green, dark purple, etc.).
3. Large area color block
(1) When screening large area color blocks, the range of 70% - 85% should be avoided, otherwise irregular dirty spots will appear.
(2) When the dot area ratio is less than 10%, it is easy to cause dot loss in the printing process.
(3) If you want to print anti white text and lines on a large area of color blocks, pay attention to the color blocks should not use colors with too high brightness, such as light yellow, light orange, or the text and lines are not easy to read.
4. Seamless connection design of continuous pattern
In the design process, sometimes we have to encounter the problem of continuous patterns. When dealing with this kind of problems, many people use local transparent effect (i.e. local non printing pattern on the film) to make up for the inaccurate cutting, or use the same color block at the edge of the packaging bag. In fact, it is also good to do so, but sometimes it will damage the continuity of the pattern and lack of aesthetic feeling.
In the design and production of continuous patterns, the size, shape, continuity and other factors should be considered. Only when the patterns are suitable, can we obtain better results. Make sure the seamless connection between the pattern and the pattern when assembling, and the continuity of the overall pattern will not be affected when cutting.
5. The use of transparent ink
Transparent ink covering power is very low, high transparency. The film printed with transparent ink generally needs composite aluminum plating film, so that the metal luster of aluminum plating film and the luster of ink are combined with each other to reflect bright colors. Moreover, from different perspectives, the color phase will have obvious changes. When observed under different light sources, the difference will be greater, which has a good shelf display effect.
6. Enlargement of front pattern
In many design cases, it is necessary to increase the front pattern. For example, the pattern and color of the front and back of the back cover bag are often different. In the design, the front pattern should be deliberately enlarged to the back, so as to avoid the back pattern appearing on the front of the packaging bag when there is deviation in the bag making process, which will affect the integrity of the main view (front) pattern.
7. Arrangement of color sequence
If the gravure printing process is used, the color sequence should be from deep to light, and the color sequence of surface printing is just the opposite. In the case of spot color, the color order of spot color should be determined according to the brightness of spot color, so as to improve the accuracy of overall pattern overprint.