Images printed with different levels of gloss are quite impactful. It gives a designer the power to point the viewer’s eyes to very specific areas within the artwork. At times, creating certain areas of gloss in a design is used as an artwork element—for example, when gloss letters are added to a solid color background as a very subtle effect. But, for brand owners, it offers the control to focus on the product, headline, price, and other important communication elements.
Printing with inkjet printers—particularly using aqueous or UV inks—has historically delivered one type of finish, typically satin. If you wanted to offer a glossy finish to the artwork, it meant going offline and adding a layer of varnish. Gloss varnish was added to the entire image or sometimes it was added to those certain areas that the customer wished to “pop” out of the image. Or, at times, the digital printer had to be stopped and reset to print the gloss areas.
After experimenting with inkjet printers and certain inks, there’s an easier way to create spot gloss images. It turns out that the curing times of some UV inks deliver different effects. In fact, if you are willing to wait a little longer on the inkjet printer—just a few seconds for the curing process—a gloss finish can be delivered rather than satin. The print shop that can offer gloss has a distinct advantage over its competitors, because a gloss finish is often a preferred effect.
Attempting spot gloss manually is very tedious and prone to error. It requires the prepress department to create two separate images—one of the satin areas and one of the gloss areas. Then the press operator RIPs and prints the two images, carefully changing the digital printer’s gloss/satin settings between the two print passes. Often, an entire run is printed in satin, and then all the half-printed substrates are returned to the printer for the gloss layer—a great way to invite misregistration.
Recent changes in the RIP and printer software make the process much simpler. With the right equipment, producing a print job with spot gloss on a UV inkjet digital printer is very similar to producing a regular print job, with just a couple of additional prepress steps. The first requires someone to edit the artwork and produce separate “masks” of the printed image areas, defining which should be gloss and which should be satin, in much the same way as would be done to create the varnish plate. While the designer who originally creates the artwork might prefer to define the gloss “layer”, many printing companies prefer to provide the service themselves as they have more experience working with the tolerances of the process.
The second step is to combine the varnish layer with the satin layer in the artwork file, so that the combined satin and gloss image is processed in the same way as a standard image—i.e.: sent to a RIP, processed, and printed using the correct machine settings. The RIP and the printer both understand which areas are gloss and which are satin—and print them accordingly, automatically using the correct UV ink curing settings.
The development of this process moves it from a manual procedure to one that is much more automated and seamless than before. Originally, the two images would have been RIPed separately to the printer, and printed consecutively. The operator would be required to make the requisite changes to the UV and other printer settings between layers, with a greater opportunity for errors to creep in.
It is worth noting that because the image is combined, there is no danger of losing registration between the two images. The inkjet printer does not stop for a second image to be loaded, where there might be a chance of the substrate moving, the file being loaded into the wrong position, or an incorrect file loaded.