The use of digital printing in blue paper and digital proofing
About the author: She Wencheng is currently the senior prepress manager of Li & Fung Accor Group. He has been a deputy production manager for Colourscan in Singapore for 14 years. After that, he worked as a technical consultant for Hong Kong Bright Platemaking Co., Ltd. for 7 years. .
As a new technical force emerging in the era of digital printing, people in the industry will not be unfamiliar when it comes to digital printing. It is easy to think of short-term quick printing, on-demand printing and variable data printing. However, I do n’t know if anyone has tried to transplant digital printing into the CTP pre-press field, leading the leading role in the front-end protagonist, and thus significantly improving efficiency, saving time, and reducing costs?
Taking Dongguan Lifeng Accor as an example, there are 4 original digital proofing equipments and 8 blue paper proofing equipments, which are specialized in proofing staff of nearly 20 people (two shifts); since the introduction of digital printing machines as proofing this year, the average production efficiency has increased by 5 times , Reduce the operating staff by nearly half.
What are the advantages of digital printing compared with ordinary proofing methods? How does it achieve a substantial increase in proofing productivity? We will start by analyzing the current situation of the industry one by one.
Current status of the industry
As we all know, Dafan CTP process covers two important front-end proofing links, namely digital proofing and blue paper proofing. The former is an important process of color monitoring, while the latter focuses on the coordination of inspection and post-printing, emphasizing large-scale paper opening, folding order, binding method, etc.
With inkjet printers and specific proofing papers, plus professional color management software, digital proofing can approximate the color effect of the final printing. With the popularization of CTP in recent years, digital proofing is also easy to operate, small in size, fast in speed and stable in quality. It is increasingly admired by experts and companies, and it is likely to replace traditional proofing. However, it is undeniable that it is limited by the special high-gloss coated proofing paper, the back side is not easy to glue, and it cannot show the texture of the final printed paper; and because of the difference in imaging and media, such as the expressive power in fluorescent colors and PMS spot colors There is still something missing.
Because of this, the tedious traditional proofing has not completely faded out of the historical stage, because its principle is more similar to printing, and more customers specify that traditional proofing is required. In fact, the proofing machine uses a round flattening and wet pressing dry process, and the DotGain is smaller, while the printing machine uses a round flattening, wet pressing wet process, DotGain is larger than traditional proofing, so these two methods There are still differences.
Blue paper proofing is also called layout proofing, which is a relatively fast but low-precision proofing that uses large prints as the output unit. More attention is paid to the speed of proofing, and the quality requirements are not high. Therefore, color management is generally not used. Compatible or alternative inks are generally used, and ordinary book paper can be used. Naturally, the resulting graphics are not fine enough to be easily proofed on both sides. After completion, "post-processing" is required, such as line cutting, double-sided alignment, paste binding, etc., which is time-consuming and time-consuming.
Both have their own emphasis, and the use of different proofing media and carriers is an indispensable and important part of the CTP process. [next]
After the introduction of digital printing and proofing
As a new proofing method, digital printing creatively integrates digital proofing and blue paper proofing into a single process, using one proofing to complete the previous two proofings. Specific reference from the following aspects.
Consumables cost: digital printing directly uses low-cost printing paper, pink paper, dumb paper, book paper, ranging from 80g to 220g, and does not require special digital proofing paper, not only can fully reproduce the texture of the final printing, but also significantly reduced Proofing costs. In addition, through the cooperation of departments, the collection or reuse of excess corner waste in the printing workshop is also a desirable way.
Proofing format: Generally speaking, digital printing presses have limited format, A4, A3 or A3 +, it seems impossible to replace the large format proofing work like blue paper proofing. However, when we consider that blue paper will eventually cut and fold the sample book, we have found an entry point to solve the problem.
Through the front-end processing of the software, for example, using the Blueline function in CreoPrinergy, the large version of the software is divided into successively suitable for digital print output format, and then proofing, and then automatically bound.
Thanks to the programmed arithmetic processing and automated equipment operation, the sample book is the same as the finished product obtained by manual folding after blue paper proofing, and many large-scale elements can still be checked. On the contrary, the colors are realistic, comparable to printed samples; the front and back sides are output at a time, and the alignment accuracy is high; the manual steps are omitted, and the efficiency is greatly improved.
Proofing quality: the same use of color management instruments and software, through correction and optimization, can be adjusted to match the printed samples. And because the digital proofing paper is exactly the same as the printing paper, the result is closer to the printing effect.
Due to the differences in imaging principles and methods of some high-end digital printing equipment, digital printing has made great progress in fluorescent and PMS spot colors compared to digital proofing, and some have achieved a match of 90% or closer.
Proofing time: Digital printing is famous for its short version and fast printing. The speed is far from that of ordinary digital proofing and blue paper proofing.
Taking an inkjet machine commonly used in the industry as an example, it takes about 35 minutes to output 16 A4 posts, while using a digital printing machine, it takes only 1 minute to proof both sides.
The normal output time of a piece of blue paper (8 × A4) is about 1 minute, because it takes time to return the paper to the paper, and it takes 4 minutes on both sides, plus a total of 8 minutes after the manual production of the sample book. The digital printing outputs both the front and back sides, and all post-processing procedures are automatically processed by the device until the finished sample book is output. The same size of blue paper only takes about 1 minute.
Operator: Two proofing links were counted before, similar to the scale of SNP Dongguan Lifeng Accor. After using digital printing, the whole process only needs one proofing, and the degree of automation of the equipment is very high. Generally two people are enough.
In addition, digital printing can bring greater freedom to printing, and can also add more value-added services, such as various on-demand quick printing, temporary reprinting, variable data printing and so on.
However, digital printing is not without defects, and the format is an obvious problem. For example, when a single page is produced, it is not conducive to binding. The service life of the equipment is short, generally only 3 to 5 years, which is no longer than 15 to 20 years for printing machines. In terms of color, compared with printed matter, the saturation is slightly higher. [next]
Investment analysis and application considerations
If you are interested in investing in prepress managers of digital printing, you also need to consider and measure the following aspects comprehensively.
Cost investment: Digital printing can achieve quality, efficiency and stability in one sign, but I believe some people will question the investment cost is too large, and the equipment worth one or two million yuan is not worth it? Should choose a flexible payment method, it is best to be bundled with equipment manufacturers to achieve benefit sharing and value win-win.
In addition, it is necessary to re-budget and prepare new consumables suitable for digital printing, as well as preliminary training for operators.
Compatibility with the original process: As a new element introduced, it is best to be compatible with the existing system. For example, we now use the CreoPrinergy process, the ideal is to use the same process.
Color management: The purpose of proofing must restore the true printing color to ensure consistency with the final printing. The color matching between digital printing and actual printing is a brand new subject, which requires considerable time and effort. When we first started using digital printing, we also wasted a lot of materials and time, and took some detours. However, we finally found a set of effective methods to optimize color matching to even exceed the original digital proofing.
Consistency: The function of the blue paper is ultimately consistent with the output zinc plate, so the settings must be noted, such as stealing, overprinting, transparency and other effects.
Scope of application: Considering a large number of proofing and automatic post-press binding, it is more suitable for commercial printing enterprises mainly based on books and magazines.
The creative application of digital printing in pre-press proofing has reduced complexity to two, and has surpassed digital proofing in color reproduction. Demonstrated its extraordinary proofing strength, blooming its unique proofing style.
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