Throughout the history of printing flexible packaging, there have been two main ways it has been accomplished: rotogravure printing (roto) and flexographic printing (flexo). Traditionally, roto has been more expensive and thought to produce a better image on packaging. Recently, flexo has made significant strides to improve this printing process, including the use of high definition (HD) photopolymer plates and an extended gamut ink system, which have enabled the flexo printing process to produce a better product at a lower cost.
The main difference between roto and flexo printing is in the plate technology. Roto uses an engraved cylinder that is prepared by etching the image area into a metal cylinder. The depressed areas are where the image is, and the surface represents the background areas. Flexo printing, on the other hand, is a method of rotary letterpress printing that employs flexible photopolymer plates, where the image is raised in relief from the background, and then a metering roller (the anilox) runs over the plate and leaves ink on the raised areas only. The raised portion makes contact with the surface to be printed, and the ink transfers from the plate to the film, leaving behind the image on the printed surface.
Understanding the basic difference between the two processes is a basis for understanding key components of flexible printing. The first term is “line print,” which is using a single color on a package. This could be either a specific branded color for a specific company or just a solid color coming from PMS or Pantone. “Process print is the use of dots to print different colors and build up the final colors to make up a picture. In the process print procedure, the printer is building a color using the three primary colors of cyan (blue), magenta (red), and yellow, with the color Black, or CMYK. Also, when doing process print jobs, there might be times when there is a necessity of having a layer of white laid down after all other colors in order to help the image stand out more.
This knowledge leads to the important improvements that in regard to HD photopolymer plates and extended gamut ink system.
HD photopolymer plates have now enhanced the ability of flexible packaging converters to create process print jobs that have sharper colors, and crisper images. These HD plates allow the printer to utilize one plate per color. Each plate will be able to lay down enough color for shadowing, as well as enough ink to match desired densities on solid colors in one plate. This allows the plate to lay down a very specific amount of ink in a very precise place on the actual image. On top of producing a superb image, these plates can also lead to cost savings. Two reasons are through the wear pattern of the plates and in the consistency of the actual photopolymer plate structure. This means that the plates do not need to be replaced as often, and they lead to less ink consumption in the printing process.
As for the use of extended gamut ink systems, in a nut shell, the print converter is taking the four main colors of process printing (CMYK) and adding two to three colors. Having these allows the printer to replicate spot colors and provide a wider range of the Pantone color palate. Through utilizing the extended gamut system, a printer can achieve more than 90% of the colors in the palate using only a few color combinations.
Also, depending on the design of the image, fewer colors are needed. Using this extended gamut system allows for many different positive aspects that are passed along to the customer, including a broader color pallet that uses fewer colors and less inks, which leads to cost savings for the customer. Using fewer colors also means there are fewer that need to be changed out, if at all, when moving from item to item. This also means quicker changeover times and leads to better efficiencies in the process.
Using the extended gamut ink system with HD plates allows the printed image to be of such a superb standard with such vibrant colors, that this leads to a product on the consumer shelf that stands out among the rest of the items. Finally, these processes lead to more of a reliable image quality from job to job.
When contemplating new products, redesigning current designs or looking for cost savings in general, one needs to take into account all aspects of what goes into a product to make it shelf-ready. When considering printing for any packaging, keep in mind the idea that HD plates and the extended gamut ink system can become a great value.
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