Ink Impacts Window Output
Progress in Window Media
By Amber E. Watson
End users continue to explore new and unique ways to market their businesses beyond standard banners and signage. Vinyl and film are used to create eye-catching window graphics to stimulate sales and improve brand recognition.
Print service providers (PSPs) utilize window graphics frequently due to media advancements providing short-term durability and expanding environment options. A variety of material is available from perforated to unperforated, static cling, adhesive backed, and clear.
Along with the media, the printer and ink sets used in window graphic production are of significant importance. UV, solvent, eco-solvent, latex, and aqueous digital printers are compatible with specific substrates. Care must be taken to match ink with the correct media.
Advancements in ink formulations directly affect window graphics. For example, white ink allows for high-quality, visible prints onto clear media. While new media and ink propel window graphic usage, challenges are apparent. Printer calibration settings must be carefully examined for each substrate used.
Ways to Use Windows
Window graphics are somewhat of a niche market, where PSPs provide an out-of-the-box approach to business offerings. Hewlett-Packard (HP) estimates that more than 60 percent of PSPs regularly print window graphics.
Jim Cain, director of sales, Polytype America Corp., believes that, in the past, window graphics were under-utilized in commercial advertising due to lack of knowhow and cost effectiveness. “The very nature of window graphics dictates that the image must be high quality and durable. Recent growth is due to high-speed meeting high quality, making window graphics widely available and cost effective.”
Windows are premium real estate for advertising. “Most commercial establishments use glass as a large part of their architecture—the ability to decorate it for corporate and brand identity is a strong suit of window graphics,” says Kevin Currier, application solutions manager, Durst Image Technology US LLC. “Using large fields of glass turns a building side or a vehicle into previously untapped promotional space.”
Terry Amerine, business development manager, wide format inks and media, graphic systems division, Fujifilm North America Corporation, points out that while more laws and regulations are passed to restrict signage, using the inside portion of a window is typically exempt.
As architectural windows become more popular in commercial installation applications, Sean Roberts, global customer experience center manager, EFI, notes that these canvases lend well to short-run marketing opportunities. The ability to easily and quickly update and replace graphics for different campaigns also makes them cost effective.
Many window decorations are temporary. Due to the relatively low cost of production and installation, frequent changes are a realistic possibility. “If the graphics are intended to advertise an event, for example, they need to be swapped out for a new message once the event is over. Frequent turnover fuels higher demand for window graphics,” adds Lily Hunter, product manager, Roland DGA Corporation.
Although window media is intended for clear or see-through surfaces, often it is used for security or privacy. “While static clings are a great way to create easy-to-apply graphics for sales and point of purchase advertisements, perforated window films are ideal for tinting on both businesses and vehicles. This creates a sense of privacy while providing a useful function for sales without detracting from an inviting appeal of a storefront,” explains Michael Maxwell, Atlanta branch manager, Mimaki USA, Inc.
Another product that adds privacy with a touch of elegance is printable etched glass vinyl. “As an office decoration, etched glass vinyl is cost effective, and may be displayed permanently or temporarily,” continues Hunter.
Considerations should be addressed prior to print to ensure the correct ink—aqueous, latex, solvent, or UV—is used with specific material. Hunter recommends determining image quality requirements, intended length of use, viewing distance, level of exposure to sunlight, and whether the graphic needs to be cut.
Amerine views heat generated by the curing or drying phase as the biggest challenge when it comes to selecting an ink. “Many materials are thin gauge, therefore, susceptible to wrinkling or shrinkage,” he explains. The more heat generated, the more vulnerable a graphic is for error.
Aqueous ink is not a popular choice for window applications due to the possibility of the ink running, especially if the appropriate overlaminate isn’t used. Latex, water based and applied with heat, does experience more use in the window graphic space. Solvent ink, also applied with heat, fuses with the media as it cools down. UV ink, cured with heat lamps, sits on top of the media when dry. Since it does not require high heat to set, UV is ideal for use with material that tends to warp.
Maxwell cites that the most common ink used with window media is solvent, but UV-curable and latex work as well. “Solvent tends to bite down in the material a bit better; UV-curable is a bit more versatile in layering the inks, like double-sided static clings; and latex works well but only if the film is receptive to the curing process,” he shares.
According to Oriol Gasch, category manager, large format printing, Americas, HP, UV printers are the most versatile for printing on clear window media. “Special techniques must be used such as applying anti-static spray and printing in reverse. If the ink is applied on the adhesive side—static cling—it creates a barrier and the film does not stick to the glass surface.”
Cain agrees that UV is one of the most forgiving inks. “It can be laid down in multiple layers, which is vital for many window applications,” he shares.
White Ink on Windows
White ink presents a range of special effects. Currier explains that many applications utilize ambient and back lighting on one- and two-sided graphics. “White is used to create solid areas, and reduced or eliminated to allow varying levels of light to enhance the graphic. White on its own is widely used for décor purposes—recreating the look of frosted glass as a privacy screen, for example.”
Reed Hecht, product manager, professional imaging, Epson, points out that, until recently, white ink was not as cost effective or as simple to use, therefore, it was not supported by the majority of sign printers.
Today’s wide format digital printers with a white ink option eliminate many of the original complexities, such as slow output, daunting maintenance requirements, and subpar quality. “Making white ink easier to use and more cost effective, combined with the introduction of new media offerings, enables local sign shops to expand the printing options for window graphics,” continues Hecht.
Rob Pinedo, West Coast technical manager, Agfa Graphics, is commonly asked by PSPs how to correctly calibrate white ink. He admits that the answer varies based on the printer and RIP. To ensure a properly calibrated device, Pinedo suggests first printing a solid white patch—large enough to apply to a window—to check its opacity.
“Most RIPs allow for varying levels of white density to be printed. With solvent printers, a longer dry time is necessary,” he recommends.
The second step in the process is to print a linearization file provided by the RIP. Today’s most popular RIPs feature a wizard-based interface for this process. “This file is chosen based on the spectrophotometer available. It needs to be printed on a full page of white ink with the desired density of white ink chosen,” adds Pinedo. Lastly, scan the printed linearization file on an opaque neutral surface. In most cases, the RIP applies the new linearization file for new jobs.
Pinedo notes that the denser the white, the higher the ink cost. Not only are consumable expenses affected, but time as well. “With solvent ink, there is a longer dry time. UV could mean cracking or chipping. It is recommended to use the lowest amount of white density to ensure that no over-inking takes place.”
The Catch with Calibration
When it comes to optimal calibration results, many PSPs rely on a good eye and the understanding of the application’s final location.
David Conrad, director of marketing, Mutoh America, Inc., states the importance of understanding the light source for the location of the window graphic. Considering if the graphic will be in direct sunlight; shaded; or if natural, synthetic, or both light sources hit it, helps calibrate the print image and improve the quality and overall look of the graphic.
“Measuring the variable amount of emitted light is not the same as placing a white board behind the clear media,” cautions Cain. Colors vary throughout every hour of the day due to differences in the amount of light coming through. “On most clear or window perforated material, a double strike is required, and there is no good procedure to profile a double strike. The best method is to use a good standard profile on white media, set it to double strike, and name it ‘profile for window material.’”
Using the proper profiles for the printer, ink, and substrate helps avoid printing pitfalls. Calibration primarily depends on the type of media utilized. “Each requires specific color calibrations and traditionally a white layer, but white media—like a white static cling—can be printed normally with a traditional CMYK setup. Clear static clings require a white layer,” says Maxwell.
According to Currier, on some perforated substrates, the ink film does not break cleanly on the perforations. While major vendors have worked to solve this, testing is still recommended before committing to a long run.
“Lowering the ink limit of the printer may help prevent this,” suggests Currier. “In addition, static cling films sometimes curl on the edges when used with some UV inks and heavy coverage images; this may require testing with one’s system prior to the final print.”
Since a percentage of the surface on perforated window material is comprised of holes, Hunter explains that it is not necessary to print in high-quality, high-pass mode. “You need better quality prints for storefront window graphics since the viewing distance is closer, but for building wraps, you can use lower resolution images.”
For clear window media, Hunter recommends higher density inks and a white flood as a base. “The white layer adds the opacity and a foundational white point required for a quality finished print.”
“White and process colors can also be manipulated to give the print a unique look, allowing for natural light or backlighting to enhance the graphic, or bumping up the vibrancy of specific colors,” adds Roberts.
For all substrates, Pinedo recommends allowing 24 hours to acclimatize the finished product. “Once the print dries, ideally, the material should be hung or left on a flat table to post cure. At this time the ink surface should be exposed to the air and not in contact with any other surface.”
When it comes to creating window output, there are many options available. Taking into account a customer’s creative vision and color or branding standards, as well as the final installation site helps determine the best media, printer, and ink for the job.
PSPs and print buyers realize that both indoor and outdoor window graphics, whether for short- or long-term applications, serve as cost-effective, versatile, and highly visible marketing vehicles. With new substrates constantly introduced and the ability to utilize various ink types evolving, window graphics gain ground.
Feb2014, Digital Output