Waterless Printing (2)

Waterless Printing, Also Known as Silicone Resin Gravure Printing Many printers believe that waterless printing is only a printing process that does not use water, but it is actually a completely different process. Flat printing utilizes a lithographic printing plate so that oil (ink) and water (covering the non-graphical portion of the printing plate) do not mix. Lithographic printing plates are often frosted to keep the amount of ink repelled in non-graphical portions. The surface of the inked graphic is thin so that the surface of the plate feels smooth. Waterless printing uses an ink-repellant silicone resin-coated printing plate, and the coating is removed at the graphic portion to make the silicone resin form a small cell, and the bottom of the cell is an ink-absorbing photopolymer. The graphic part that contains the ink is concave, the same as that of gravure printing. Since the non-graphical portion of the plate is in the silicone resin layer and the inked portion is in the recess formed by the grease, this process is somewhat like gravure printing. Differences in plate material, structure, and basic process methods all lead to different characteristics of the lithography and waterless printing processes. Each process requires different ink properties and printing environment. The balance between water and ink is a problem in plain printing, and waterless printing is demanding to ensure the temperature. The silicone gravure has a recessed honeycomb structure that can hold more ink on the printing plate, so the density of the printed ink is higher. Both the waterless printing and the printing ink density on the ground will lead to an increase in the dot gain rate. However, due to the difference in the printing plate structure, the waterless printing under the same ink conditions is smaller than other methods. (When the ink density is the same, waterless printing has a smaller dot gain than plain printing.) For any kind of printing, when the ink is transferred to the blanket, the graphics part needs a certain amount of pressure. The ink in the lithography is present on the surface of the printing plate, without any support structure at the edge of the reticle, and the woven spot must expand to the side when being squashed, resulting in the expansion of the mechanical dots. The well-like structure of the ink in the waterless printing provides a support for the network of edge walls. Therefore, when the dots on the unwatermarked version are squeezed, the edge wall reduces the dot gain. Due to the high viscosity of the waterless printing ink, the dot spread when the image is transferred from the blanket to the paper surface is also slight. Dot enlargement also occurs when the paper absorbs ink, and the dot shape may also be distorted. The embossing ink also undergoes emulsification with a certain degree of process, resulting in dot gain and deformation. Silicone gravure does not use water, the ink will not emulsify. Therefore, the ink is oxidized and dried rather than absorbed. The difference in the dot expansion between the two is particularly evident on non-coated paper. One of the most important advantages of waterless printing is the ability to print at high screen lines (above 300 dpi). The lower dot gain rate and the use of silicone coating to create non-text graphics are the reasons why waterless printing can use higher screen lines. The method for creating a dot on a waterless version is to remove the silicone resin to expose the polymer honeycomb surface of the ink. The non-graphic part is the print version, which creates better outlets. In the lithography, the ink must be wetted in order to extinguish the non-graphical portion. Moreover, the offset printing dots are often as small as less than 10 microns, so that a higher resolution offset printing will ensure a stable and correct supply of water. Although removing the silicone resin at the micron-scale dots on the unwatermarked version requires very complicated high-quality layout processing steps, it will result in a plate with a high number of lines. The technical difference between waterless printing and lithography is not to use water, use silicone to create non-graphical areas, and to use recessed portions in gravure to protect the ink in several ways. Silicone gravure printing, or waterless printing, can be divided into three categories according to the different methods of platemaking: typical UV-exposed platemaking simulations and ordinary waterless printing plates in the plate room. The only vendor currently simulating a waterless version is Toray Industries. The digital waterless version is divided into two types depending on whether a computer-to-plate (CTP) device is used on a printing press or a printer. The online process often refers to direct printing, while the offline process is the so-called computer-to-water version (CTWP). Many digital waterless versions are being improved and tested. Currently only Presstek can supply plates, and the company's Pearl Dry plate can be used in both processes. Waterless printing, also known as the status of the gravure printing of silicone resin and the acceptance of the situation, is largely procedurally dependent on the process of plate making—simulation, direct printing, or CTWP. Note: The American Waterless Printing Association - WPA can provide a lot of information about waterless printing. We can get it from the association's website, which publishes a technical manual on waterless printing - "Complete Guide to Waterless Printing", by John O`Rourlce. For non-WPA members, price: $89; WPA membership, price -$69.