Sample proofs are the weight basis of the quality control of the printed matter and the tools for communication and communication with the customer. Its role is mainly reflected in the following two aspects.
For one, proofs can help users check the various information contained in a document for possible modification, such as fonts, images, colors, and settings for all pages. Among them, the color is the most difficult to control in the proofing, because different substrates, inks and dot gains will cause changes in the color of the proofs.
Second, proofs can be used as contracts between customers and printers. The same sheet should accurately provide the same color as the final printed product, and the same sheet should be printed shortly before the printing so as to avoid discoloration and distortion of the proof due to the long storage time.
Gravure printing method
Proofing is the link between prepress production and printing. It allows users to anticipate the effects of the final print before printing. At present, the proofing methods commonly used in the gravure printing industry include soft proofing, traditional proofing and digital proofing.
1. Soft proofing
Soft proofing is implemented on a color display and is undoubtedly one of the most convenient, fastest and cheapest proofing methods, but it requires a color monitor with high accuracy and must be correctly calibrated.
The obvious disadvantages of the soft proofing method are: low resolution, only 72 dpi; the accuracy of the color depends on the performance and calibration of the display; it can not provide a reference to the hard copy of the printing process.
2. Traditional proofing
There are two kinds of traditional gravure proofing methods commonly used, as shown in Figure 1, one is gravure proofing, the color proofs obtained are accurate, high reference, but this proofing method requires grinding, electric carving, electroplating and other processes, The requirements for the processing precision of the plate cylinder are high, the cost of electroplating is high, and the process is complicated. Therefore, the production cost of this kind of proofing method is high and the cycle is relatively long, and it takes at least one day.
Figure 1 Traditional Gravure Printing
Another method is offset proofing. This method requires the output of the film and the printing plate, and then the proofing is done on the offset proofer. Although this method can reduce a part of the production cost, due to the difference between the offset printing and the gravure printing process, the proofing effect is also quite different. The actual density is insufficient and the color levels are more equal.
The advantages of traditional proofing mainly include the following points.
(1) The production process of proofing and printing is relatively close.
(2) The same rasterization data is used for proofing and printing. Potential problems such as moire, typography and fonts can be identified by proofing.
(3) Good performance in trapping and ink opacity when spot color and metallic colors are used for proofing.
The disadvantages of traditional proofing mainly include the following points.
(1) High technical content requires professional technicians to obtain accurate proofs and labor intensity.
(2) Requires higher investment.
(3) There are many processes involved, the cost is high, and the processing cycle is long.
(to be continued)
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