It’s time to come clean — if you’ve ever tried using PVC plotter film with your solvent, eco-solvent or UV-curable printer, raise your hand. We’ve all been there. When there’s a hot job on the queue, it’s tempting to use whatever film is hanging in the rack. The customer won’t know the difference, right?
Derail that train of thought. You’ve invested too much in the digital process, which includes equipment, training and relationship building, to risk it all on poor film choice.
Not all films are created equal. To protect your equipment investment, choose a film that’s engineered to succeed in the digital process — PVC inkjet media.
Because the media primarily dictates image quality, and its appearance makes the final impression on your customer, making the informed choice is critical. This column explores what makes pressure-sensitive-adhesive (PSA) plotter film (also referred to as "marking film") and PSA inkjet media fundamentally different from a manufacturing and composition standpoint, and how these differences impact image outcome.
Why use plotter films?
Why would a shop use plotter film for an inkjet application, for which it’s not designed? Simply put, a lower price point. Providers may believe, because the invoice is less, they’re saving money. Standard, white plotter films will get the job done, but the job won’t be done efficiently. And, the choice you thought would save money incurs greater labor and production costs — and could hurt the client relationship.Advertisement
Mistakes will occur, because most providers who print on plotter films create an inferior product or destroy the application. In reality, marketplace advancements have reduced the cost difference between digital media and plotter film to pennies on the dollar.
Wade Davis, the owner of Image Graphics 2000 (Ft. Lauderdale, FL), said, "Some printers who use plotter films for digital jobs may think they’re saving money because plotter-film rolls are somewhat cheaper. But if they have to run off more media to compensate for errors, such as image quality or splices, they’ll exceed the cost of appropriate digital media."
According to Laura Wilson, supplies manager for Roland DGA Corporation (Irvine, CA), most applications that use inkjet media range from 30 to 95 cents per square foot. Combined with ink, the provider’s cost to digitally print vinyl graphics ranges from 60 cents to $1.70 per square foot. With retail prices that range from $6 to $20 per square foot, these jobs generate a nice profit when done correctly.
To do the job right, you need to know the major differences between plotter PSA vinyl and digital PSA vinyl, which are literally ingrained in the films. Although they share similar coating processes, actual production vastly differs.
"While the PVC film’s structure doesn’t change, differences in quality, surface tension and other factors depend a great deal on the type and manufacture of the media," Wilson said. "Users don’t always know this, so they stick with cheaper, generally less compatible films, such as all-purpose plotter films."Advertisement
For example, production speeds differ. Plotter films can be coated at high speeds; however, digital films need to be coated at a slower pace in order to prevent facestock defects such as "fish eyes" (mottled, crater-like formations), color shifts or other inconsistencies. While these defects can be tolerated in plotter films, they’re deadly in inkjet media.
"Think about mid-range printers 24 to 74 in. wide as basically large desktop printers. They’re shooting ink onto the surface to make an image," says Wilson. "What’s on the media surface will affect the print, and graphic standards in many industries are increasing as quality increases."
This expectation trickles down to the final customer, who demands a more favorable final print. Many plotter-film imperfections aren’t visible. However, during the printing process, these little imperfections lead to what I call the "Easter egg effect." Remember how the dye wouldn’t stick to your egg after using your wax pencil? The same thing happens when the ink hits a media imperfection.
Digital film’s lower production speed maintains surface tension to form a smooth print surface, which is key for ultimate dpi reproduction and ink acceptance.
Also, slower speeds help eliminate static, which can wreak havoc with printheads. Plotter film’s faster production speed generates static electricity, which is stored in the film. In turn, when the same films are used in the printing process, the uneven build-up of static electricity alters printhead performance.
And, the differences don’t end with the coating line. Once coated, vinyl films need to be cut and transferred to individual rolls. To optimize a plotter-film batch, some manufacturers splice shorter pieces together to form a complete roll. With most cut-vinyl applications, you can avoid these splices by effectively arranging objects to be cut on the roll.Advertisement
In digital printing, however, this isn’t an option. Splices mean botched prints and machine downtime, which hurt both you and your customer. Unfortunately, some digital media still contain splices. Always check your roll for splices before loading it on your machine.
Paper plays a role
It’s a good practice to build things from the bottom up. In this case, consider the liner as the bottom. People don’t pay enough attention to the liner — this portion of the film is as important, if not more so, than the printing surface.
Digital media typically include a high-quality, kraft-paper liner, which is typically silicone-coated. To minimize cost, many plotter-film manufacturers use a lower grade of kraft paper.
For such traditional applications as plotting and weeding, the lower-caliber liner isn’t much of a factor. However, a higher-grade liner has a huge impact on printing applications because it provides necessary features, such as a textured surface to properly feed media, and extra coatings that protect against moisture, static electricity and ink migration.
Higher-grade liners also affect ink acceptance. For example, they accept additional heat during the printing process, which opens the pores of the media for better color saturation. Also, digital products can withstand more ink saturation than plotter films, which may not possess the structural integrity to handle the solvents and processing steps that films undergo during digital printing.
Making it stick
From the liner to the facestock, digital-media manufacturers create components that ensure successful printing, including the adhesive. At print shops, many installers enjoy the switch to digital films, which offer more adhesive systems for various applications. Because most digital prints are installed in large sheets, a permanent adhesive, which is typically found in plotter film, isn’t always the best solution. To aid the installation process, most manufacturers offer removable, repositionable adhesives.
An adhesive specially formulated to enhance the printing and application process also coats most inkjet media. White plotter films probably have clear adhesives, whereas most inkjet films feature a gray or opaque adhesive that makes the white film appear brighter and helps cover the surface beneath the film.
Here’s where it gets technical, so put on a rocket-science cap. Because plotter PSA vinyl isn’t engineered expressly for digital printing, users will be hard-pressed to find appropriate color profiles. With the digital process, each combination of printer, ink, RIP software and media produces a different result.
To ease the user’s pain of trying to successfully calibrate all factors to produce an acceptable print, many hardware, software, ink and media companies make substantial investments to develop these profiles. This gives the user a "plug-and-play" solution that offers a higher likelihood of success.
"There’s no shortcut to getting good color," Eyal Friedman, director of technical services for SA International (Philadelphia), said. "Factors such as printer temperature, driver options, dpi and dot size all affect the print. ICC profiles are engineered to consolidate all the information and provide the printer with the data it needs to lay down the right amount of ink."Scanvec Amiable
Most, if not all, of these developed profiles were established for inkjet media, which is what printer and ink manufacturers endorse. Consequently, in lieu of studies, there’s no guarantee that the combination of inks and plotter media will last. This brings us to warranties.
Today, most media manufacturers have developed a system of products for digital applications, or, at the very least, comprehensive guidelines to create acceptable applications. For the most part, these guidelines must be obeyed to legitimize the warranty, which printers can use as an added layer of protection for both their shop and customers. Most manufacturers’ warranties don’t support the use of plotter films for digital applications.
According to Friedman, "Profiles aren’t typically created for marking films. Even if shops successfully print on these films, the one time there’s a defect, the shop is liable."
A print shop should not use plotter films for digital jobs because the media manufacturer won’t provide a warranty. Davis said, "That kind of media isn’t intended to be used for digital printing. Printers are running a risk when using plotter films without a warranty, which can translate into unhappy customers."
Ultimately, the main goal is to make customers happy. The more you can learn about the different materials on the market and how they’re used, the more you can offer your customer. Keep in mind that your customers are not only looking for a product, but also a graphic solution for their business.
About the author
Craig Campbell is a product manager for Oracal USA (Jacksonville Beach, FL), where his duties include supervising research and product development, as well as providing support services and promotions for the signage and digital-print markets. Prior to joining Oracal, Campbell spent nine years "in the trenches," where he managed the production departments of various-size sign companies in the Southeast. For more information, please e-mail firstname.lastname@example.org.
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