Windows are more than just a means to see out into the world or inside a building. They are now a valuable piece of property used to advertise a company, brand, product, promotion, or event. There are two main types of window media in the digital print space, perforated and non-perforated. Both products are broken down into clear, pressure-sensitive, adhesive-backed film or static cling.
To successfully print to either media requires choosing among many factors. Intended application—outside or inside, in direct sunlight, car or building; RIP and profiles used to control color; print environment; ink; and available dry time are all important considerations. Certain tips and tricks aid print service providers (PSPs) when it comes to matching the media type to the job, as well as how to avoid common pitfalls during various stages of the production process.
Window Media Improvements
As window media has grown in popularity, its construction has evolved. Many facets of the product continue to change to make application and printing more user friendly, for example—liners. “It is best to use a film with a poly-coated liner over a film with a synthetic liner due to heat related issues,” says Rob Moore, national digital account manager, Arlon Graphics, LLC.
Jodi Sawyer, product manager, FLEXcon, recommends perforated products with solid liners when printing at high speeds in large sheets.
Products such as Drytac Corporation’s ViziPrint offer a clear, self-adhesive polyester film optimized for UV flatbed printing. Its textured release liner imparts an air egress in the adhesive and allows for simple, dry installation, repositioning, and clean removal.
Calendered films as a whole continue to improve. PSPs now work with thinner, more flexible products with less shrinking and better weatherability. “Polymeric or high-grade calendered films now exhibit a similar performance to cast,” says Laura Schied, marketing manager, Renolit. She notes that different tips apply for each type of calendered film, whether for perforated media, clear vinyl, or glass etch effect. “The printability of perforated films, for instance, is less sensitive to visible defects. From very close range the human eye tends to look at what is behind the image, instead of the image itself,” she explains.
Eco-friendly products are now a consideration. PSPs and customers may also choose a more environmental route. “Nearly all oil-based films landfill after use with long degradation times,” shares Alex Dowdeswell, CEO, Natural AdCampaign Ltd. The company offers the TierraFilm series of non-petroleum based films.
Not every window film is vinyl. The majority of Lintec Corporation of America’s portfolio is PET. Jim Halloran, VP sales and marketing, Lintec, notices a shift from vinyl to PET. “PET is a more stable polymer than PVC/vinyl. It is clearer and a scratch resistant coating can be applied on top. It doesn’t crack in the cold and barely shrinks in the heat,” he shares.
While each type of window film presents challenges, perforated media carries unique requirements. Several issues originate in the design phase. “Great output begins with the graphic designer accounting for the typical viewing distance, lighting behind the window, and the complexity of the image in terms of design and color,” says Jim Odden, technical service representative, 3M Commercial Graphics.
“Graphics printed on perforated window films look less vibrant than those printed on solid vinyl because up to 50 percent of the material is missing due to the perforation process,” explains Jeffrey Stadelman, technical marketing manager, MACtac Graphic Products. Adjustments to the printing process improve this by increasing the contrast of the print ten to 20 percent, he adds. Keep in mind, however, that increasing the contrast does not equate to increasing the ink limits.
Depending on the design, a specific perforation pattern may work best over another. Artwork with text, intricate designs, fine detail, and small type, for instance, are not suitable for films with a 50/50 perforation pattern. “When including text, the rule of thumb is to use a point size of 30 or larger for 65/35 or 70/30 films, and 50 or larger for 60/40 or 50/50,” advises Judy Bellah, public relations manager, Clear Focus Imaging, Inc.
Certain perforated patterns are approved for different applications. For example, 50/50 is okay for motor vehicle use, because it is essential that the driver and passengers see out a window. Janelle Falbe, marketing specialist, FDC Graphic Films, Inc., says it is up to the PSP to select the correct hole pattern for the design and application. The company recommends higher surface-to-perforation patterns for closely viewed projects.
The Right Amount of Color
Achieving the correct color density is an important part of the print process. This is managed by matching profiles. Profiles may not be available for every printer/RIP/media combination. David Timmerman, West Coast technical services representative, Avery Dennison Graphics and Reflective Solutions, advises PSPs to do their homework. “Consult your media provider for available profiles. Also, check with your printer provider and RIP companies as they may have profiles available for similar media,” he shares.
Las Vegas, NV-based PSP, Off The Wall Signs and Graphics, relies on an efficient profile created by its media manufacturer’s technical engineering team. “Arlon’s profile generates the correct amount of ink saturation on the material. Oversaturating perforated window film breaks it down and creates a tough situation for the installation team,” explains Rocky Faith, co-owner, Off The Wall. “We had problems with oversaturating prints before using Arlon’s material, so this is a win for us in terms of cost savings with ink and the efficiency it creates during application.”
Sergio DeSoto, CEO, The Bad Wrap, uses Oracal USA window media regularly. He stresses the importance of owning a RIP solution that offers the ability to write one’s own profiles and calibrate machines in house, along with placing monitors at each design station. “Document the settings for the RIP when printing on specialty films and color specific jobs. Once the art is right, you should never have to adjust. Most tweaking can be done on the RIP side,” he says.
DeSoto reminds print providers that nothing substitutes properly calibrated and up-to-date equipment and software. His tips for printing to specialty films include checking the manufacturer’s tolerances for temperature and humidity to ensure a proper print environment. For those trying to match a clear or perforated film to another substrate, he recommends running samples with the saturation and heat adjusted prior to printing the entire project.
A variety of inks are used to successfully print window graphics, including solvent, eco-solvent, thermal transfer, UV, and latex. When choosing the best ink/media combination, several factors must be taken into consideration, such as desired print durability and whether the application is for interior or exterior use.
A general consensus is that solvent inks work best for window graphics and are compatible with the majority of available media. “Solvent inkjet is preferred for applications requiring a high degree of durability, for example, bus window advertising, which is subjected to heavy washing machinery,” says Roland Hill, chairman and managing director, Contra Vision Ltd.
“Solvent printers usually print seamlessly onto window perforated film,” agrees Jaime Giannantonio Sherman, marketing manager, Ultraflex Systems, Inc. “It offers a pop of color and does not clog perforations.”
Perforated window film allows ink to seep through the holes and onto the film’s liner. While solvent is able to avoid clogging the holes, UV ink presents more of a challenge for users of this media. “UV-curable inks require a special liner, such as a double-layer perforated liner, to trap ink below the perforated layer,” shares Dione Metnick, product manager, LexJet Corporation.
Several manufacturers offer solutions to accommodate PSPs with UV-curable printers. For instance, many Avery Dennison perforated window films come with a PET liner, which helps avoid clogging or bridging of the ink in the holes. The PET liner is developed specifically for UV, solvent, and eco-solvent printers.
Clear Focus’ patented dual-layer liner, which is supplied with its line of premium window films, consists of clear PET film laminated to perforated paper to absorb ink. It also provides EconoVue with a clear PET liner.
Contra Vision Open perforated window film with open holes is printable on any inkjet printing machine and aids in the drying process. It has an ink collector, sometimes referred to as a gutter or “mesh kit” that catches ink that passes through the holes. This patent-pending product includes a black liner, having several advantages including potential use on the outside or the inside of windows.
Ultraflex developed Ultravision 6040 UV, a UV printable window film with a three way liner to allow the middle liner to catch the inks while not clogging holes or prohibiting the back adhesive layer to peel off.
If UV ink does cure in the holes, Moore suggests applying application tape. “This generally eliminates the ink when the tape is removed,” he shares.
Without perforations, clear vinyl window film is able to be printed with solvent, latex, or UV ink a bit easier. Companies such as Lintec offer different product lines for running eco-solvent inks versus UV inkjet. For PET materials Halloran recommends UV inkjet. However, many customers run eco-solvent with success as well. “With the introduction of latex and white ink that could change,” he notes.
White and Metallic Inks
White and metallic inks are fairly new to the space and present PSPs with added options as well as additional challenges. As Falbe points out, “white and metallic inks increase printing options, but can slow production speed.”
Stadelman explains that white ink offers PSPs the ability to print onto clear film, flood coat white, and then reprint over the white inks to create a single graphic print viewed from two sides.
“White inks are typically used in conjunction with clear perforated material for products to be applied to the inside of a window. This is following reverse printing of the design—to be right reading from outside the window,” says Hill. For example, white ink is applied by UV inkjet or screenprinting to make a Contra Vision Backlite product, or white and black ink applied to make a one way vision product.
Shaun Gath, director, Flying Monk Graphics, located in the UK, views registration, white ink, and multi-layer printing as the three most important topics to consider before investing in a new machine. “The biggest challenge is doing your homework when buying a machine. If a PSP does not have white ink, the full range of window graphics is not achievable,” he says.
“PSPs can only print using the hardware they already own—this means many are limited to offer only perforated vinyl and are not able to print on clear film because they do not have white ink capability—a must have for clear perforated or clear film,” continues Gath.
“Transparency is always an issue when creating window graphics,” says Marc Oosterhuis, CEO, Drytac. “Depending on the level of transparency desired, printers can add more or less white ink or use a white, self-adhesive vinyl backer. White ink allows window graphics to be printed and installed without the need for a backing film to make them opaque. This saves PSPs time and money,” he adds.
“The application of a white background coat on unperforated PVC and other clear window films often enhances the vibrancy of the colors,” explains Bellah. “White ink is a great tool when printing on clear film,” agrees Odden. “The printer can create one way vision graphics by printing the back with white, as well as perform two-sided printing by reversing the image and printing a white layer between.”