Inkjet Printing: Choosing the right films for window graphics

Photos courtesy Exopack Advanced Coatings

Photos courtesy Exopack Advanced Coatings

By Jennifer Chagnon
Point-of-purchase (POP) graphics and displays continue to provide a major revenue-generating opportunity for signmakers. According to the Specialty Graphic Imaging Association’s (SGIA’s) recently published 2013 Market Trends & Product Specialties Benchmarking Report, retail stores currently represent the largest market served by sign and graphics companies, while banners, indoor wall graphics and window displays are among the product categories that see the highest demand.

It is a particularly opportune time to take a fresh look at window graphics. While they are not a new application in themselves, the availability of new and improved inks, media, printing hardware and software has raised their achievable quality to a new level.

With today’s digital inkjet printing technologies, signmakers can easily produce one-of-a-kind display graphics to meet regional marketing requirements, as graphic alterations are significantly more cost-efficient than with traditional offset printing.

On the other hand, the emergence of the digital imaging marketplace and all of its new technologies has also made it more challenging for signmakers to select the right media for window graphics. With that in mind, the following are tips for specifying and creating eye-catching window graphics that can be easily mounted and displayed by clients.

Media options
Today’s digitally printable media offerings cover a wide range of materials, textures and adhesion options from many manufacturers, all of which can dramatically affect the look of window graphics. Applications can be produced using clear films, textiles, repositionable polypropylene (PP) and perforated films, among others. It is important to understand the differences before choosing the option that best fits the requirements of the intended job.

Textiles can yield high image density, superb colour gamut and a soft appearance. These traits have made them a popular choice today for the printing of window graphics and displays, among other POP applications.

When choosing among textile offerings, signmakers should select media constructed of 100 per cent polyester-woven fabric. Polyester adds durability and dimensional stability.

When clear films are applied to windows, they require a two-sided, pressure-sensitive, optically clear adhesive.

When clear films are applied to windows, they require a two-sided, pressure-sensitive, optically clear adhesive.

Many printable substrate manufacturers now offer repositionable textiles with a low-tack, non-permanent, pressure-sensitive adhesive and a paper liner for easy mounting. For signmakers who choose this option, it is very important to look for materials that can print ‘full-bleed,’ will not shrink with the application of heat and are designed to prevent edge curling. By allowing the material to the reapplied and repositioned countless times, the low-tack adhesive makes it ideal for both window and wall decal applications.

Clear films
Clear films have become increasingly popular for a number of POP applications, including not only window graphics, but also backlit (‘lightbox’) graphics, colour overlays and screen positives, because they enable strong black printing densities. When applied to windows, they require a two-sided, pressure-sensitive, optically clear adhesive.

There are many clear films on the market today for solvent-based, eco-solvent, durable aqueous ‘latex’ and ultraviolet-curing (UV-curing) inkjet printing systems. Polyester films are the best option, as they deliver the smoothest base uniformity and highest resolution for printed graphics. With the environment in mind, an increasing number of recyclable polyester films have become available.

It is important to note, however, some inkjet printers cannot ‘see’ clear films with their optical sensing/detection mechanisms. For these cases, media manufacturers offer films with edge stripes or a paper interleaf, which add sufficient opacity for the film to be recognized as it is fed through the printer. The stripes are the best option for printers that use edge media sensing, while the interleaf is a good backup measure.

That said, for signmakers who do not wish to use edge stripes or interleaves with their printing systems, many substrate manufacturers also offer clear films with a slight degree of opacity.

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