We need to make clear that there are several different printing systems. The most used ones are Offset and Digital; the first one is the most used and the second one is needed, in general, for certain particular cases.
Offset system has many advantages. Some of them are low cost, freedom when using the paper, color variety and the possibility of making print runs of different dimensions. It is generally recommended for long print runs. Its greatest feature is that it is possible to print using direct ink, and it helps to achieve a high quality and consistent image. It can be used on different surfaces beyond paper; thus, it is sometimes used to print on cloth or wood. Then, since the sheets are easily made and quite long-lasting, costs are lowered. Its main disadvantage may be that it has limited implementation times, as well as high short print run costs.
Digital system is more specifically used. It is essentially recommended for small, urgent or changing data print runs. Its printing times are very short. It is generally more expensive than Offset but, if it is used in short print runs, it is usually more affordable than offset (mostly due to the Offset sheet expenses). Its disadvantages are usually having a low quality in comparison with Offset, being limited as regards surfaces to print on or paper range, being delicate with finishes and sometimes leaving cracks on single-colored masses. In short: it is deficient in gradations, very thin weaves or color masses. In some of these cases, printing in Offset is better.
The most usual system is Offset and it is generally the one you will find more on printing market. Thus, we will spend more time on it.
Offset printing works by means of an aluminum plate through which ink is applied under pressure. There are usually several plates, as well as cylinders of different colors. There are usually four colored cylinders for each of the four basic colors the system works with: black, magenta, cyan and yellow. For the plate to be impregnated with ink where required, a water-repellent photochemical process is used. Thus, the sheet goes first through a moistener tank, soaking it with water and then through an inkwell. Since the ink is an oil compound, water repels it and the ink remains only on the image parts. The inking images are transferred to a rubber lining another cylinder. This rubber comes into contact with the paper, printing it through back pressure.
Today, digital/analogical systems are used; thus, the image reading system is usually carried out digitally. This allows you to convert your image into JPG; TIF or CMYK format, saved on a CD or diskette. But the system works through a printing analogy traditional system. This transference from one system to the other is carried out through two conversions:
Digital pixel conversion into a network or bit map.
The conversion of any color shade into the basic colors the printer works with (cyan, magenta, yellow, black), that is to say, a color separation process.
The transference of the original to a film is carried out through a specific system (RIP), estimating the needed map bits. On the other hand, the recorder draws the bits on the printer plate or on the film, depending on the case. As in color photography system, the recorder draws four films for each image. Each film belongs to a shade of the original, separated through the color conversion (cyan, magenta, yellow, black) and through the addition of this four blended colors, the original image is obtained. Therefore, all Offset colors are obtained from these four shaded blended combinations.
Then, we have, for instance:
Magenta + Cyan = Purple
Yellow + Magenta = Red
Yellow + Cyan = Green
In the Offset process, what we see as a variety of colors and shades is just a combination of thousands of networks of different colors varying among themselves. All this results in a solid and consistent printing in the Offset system. Although it basically works from a system inherited from the printing origins, it is still the best and most lasting one.
However, you may wish to print through a digital system. According to the variables mentioned (and, to a great extent, your urgency), the idea is that you can determine what system best meets your need. Take into account that the more time you spend on the whole process, the more effective the work will be.
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