Since printing was the first form of mass communication and contributed to the beginning of the modern era in human history, it has a crucial role in humanity's existence.
Johannes Gutenberg, who used moveable type for the first time in printing in 1439, is credited with creating it.
Since then, printing has undergone significant transformation and is now just one among several means of mass communication. Even if there are many options today, print is still a vital component of society and a crucial tool for marketing and the media.
The Fundamentals of the Printing Process
Indirect Versus Direct Printing
The method of image transfer and the type of image carrier that is often used set apart the five main printing processes. The printed image is either directly or indirectly transmitted to the substrate depending on the method.
Gravure, flexography, screen printing, and letterpress printing methods are all forms of direct printing, in which the image is transferred directly from the image carrier to the substrate.
The image is first transferred from the image carrier to the blanket cylinder and then to the substrate in indirect, or offset, printing. The predominant printing technology at the moment is lithography, which uses an indirect (offset) method.
Generally speaking, image plates can be categorized as relief, planographic, intaglio, or screen.
- The image or printing area is elevated above the surrounding areas during relief printing. Relief printing techniques include flexography and letterpress.
- The image and nonimage portions of planographic printing are on the same plane. Physiochemical characteristics that are different between the image and nonimage parts characterize them.
- In the intaglio technique, the substrate's surface is shared by the nonprinting region, and the printing area, which consists of minute wells that have been etched or engraved and have varying depths and/or sizes, is recessed. Intaglio is a method used in gravure.
- By forcing ink through a porous mesh that contains the graphic or typographic image, the image is transferred to the substrate in the screening process (also known as porous printing).
The Steps Involved in Printing
Prepress, press, and post-press steps are separated into separate printing processes.
Prepress describes all the activities involved in print production between the time files are sent to the printer and the printing itself. Receiving media files, producing proofs for inspection and approval, making any last-minute adjustments or edits, manufacturing the plates for the offset press, etc., are a few examples of these tasks.
The print-ready files are given to the prepress or media department for final preparation and proofreading before printing once the work is finished.
Here, the files will be examined to make sure that the photos are CMYK and not RGB and that their resolution is sufficient for sharp printing. Fonts will be reviewed, along with their inclusion, bleed, crop marks, and the addition of printing color bars.
The document will also receive the proper application of trapping, knockout, imposition, and origination to ensure that accommodations are made for the printing procedure, the paper type, and any additional finishing or other processes that will take place later in the production process.
To make sure everything has been received correctly and is prepared for printing, a final proof will also be created. A PDF, digital contract proof, or even a wet proof could be used as this evidence.
The project moves forward to production once the client has reviewed and approved the proof. If the item is to be litho-printed, this will entail the creation of printing plates. The item can be sent directly to the queue of the machine it will be printed on if digital printing or big format printing is employed because no printing plates are needed.
Four printing plates are a minimum need for full-color litho printing. The four process colors are cyan, magenta, yellow, and black, one for each. To ensure that the printed image is reproduced correctly and accurately, these plates will each be made up of a unique configuration of dots that are presented at particular screen angles.
The plates, which are constructed from recyclable aluminum sheets, are entirely flat and have no relief (i.e. raised surfaces). In order to print, these plates are then wrapped around the plate cylinder in the press.
Printing (offset vs. digital)
In reality, full-color printing is an optical and mental ruse. Actually, only four colors are used to create a full-color image (cyan, magenta, yellow and black). Overtop of one another, these four colors are printed in a precise dot pattern. Half-tones, or different dot sizes for each color, can either make a color look stronger or lighter. The other three process colors can be combined with them to give them the appearance of having multiple colors to the human eye.
Today, a wide variety of printing methods are available. These include offset lithography, digital printing, big format, gravure, flexography, screen printing, and pad printing.
The most widely used printing method is offset lithography, which is preferred for producing high-quality materials including direct mail, periodicals, pamphlets, and brochures. The other methods are gravure for printing very long-run publications like Sunday supplements, screen printing and pad printing for printing on goods like garments and mugs, and flexography for printing on items like crisp packets.
Another significant player in the business nowadays is digital printing. Since their launch over 20 years ago, the quality of reproduction from these devices has improved significantly. This means that, in some cases, the untrained eye cannot tell the difference between its quality and an offset litho equivalent. When you require modest run sizes of a document fast, digital printing shines. They are perfect for printing on demand, completely personalized documents like direct mail, and unique items like single books.
Printing plates for offset litho are secured around a plate cylinder within a printing press. A number of ink and damping (water) rollers are placed on either side of the plate cylinder. These rollers apply water and ink to the plate. The oily ink is carried by the water and clings to the plate's pictured portions. When the plate cylinder rotates, the ink image is offset onto a rubber blanket cylinder, which then offsets the image onto the sheet of paper fed below it.
When complete, a printed item is categorized as either portrait (taller than it is wide) or landscape (wider than it is tall).
The item's claimed page count depends on how it is completed. A4 sheets printed on just one side are referred to as "1pp" (printed pages), whereas the same item printed on both sides is referred to as "2pp." The item would become 4pp if it were then folded in half. There are many terms that describe how something is folded, such as gate-fold, concertina, and roll folds.
Binding is yet another important factor. The number of pages, the purpose for which the document is intended, and the appearance you want for your documents will all influence the sort of binding that is employed. Saddle stitching is the most popular binding technique when there are few pages. Saddle stitching involves inserting wire stitches at the fold of the spine (similar to a staple). Perfect binding and thread stitching are some other typical techniques. These techniques use glue or a stitching technique to bind the document's pages together, and they may be identified by their square spines.
Documents with special finishes have a distinctive appearance and feel. Documents with gold or silver foiling have more glitz and exclusivity. Adding a layer of tactility or protection to objects is lamination. And creating a pleasing and delicate raised or recessed surface by debossing or embossing.
Use of Chemicals
Depending on the operation, various chemicals are used in each procedure.
- Photoprocessing chemicals and solutions are commonly used in prepress procedures.
- The two most common types of chemicals utilized during press operations are inks and cleaning solvents.
- The number of adhesives used in post-press operations might be significant, depending on the finishing work required. This is especially true when it comes to the publication of books and directories.
The two chemical categories that are used most frequently in a typical printing facility are inks and organic cleaning solvents. A significant portion of the chemicals used in the printing industry poses risks to the environment and human health.