Advancements to ink sets and media promise to add durability and longer useful life to digitally printed output. However, the need for protective coatings—in liquid or film form—are still necessary to protect prints from a variety of conditions, including UV rays, graffiti, and fingerprints. This step can also add aesthetic value to overall finish.
Protective films and liquid coatings are designed to enhance a print for many reasons; the most common is protection against outside elements, including UV rays, weather, and temperature. Protection against abrasion is also popular for graphics prone to scuffing. Additionally, films and coatings are often attributed to easier installation, as materials become easier to handle with an increase in thickness.
Beyond application-based concerns, new demands and innovations in the graphic arts affect the useful life and durability of media. For instance, environmentally friendly alternatives to PVC, such as polyolefin, have a relatively short life, notes Ritchie Daize, international account manager, Arlon Graphics, LLC. Protective films help extend the service life of these products. Daize notes that companies like Arlon continue to develop “green” protective films.
Judy Bellah, public relations manager, Clear Focus Imaging, Inc., also notices a trend of milder ink sets—such as eco-solvent, mild-solvent, and latex ink—which increase a need for protective films and coatings. “Continued growth in the vehicle wrap market has also boosted demand for overlaminates, which are used to increase the life of the graphics and—in the case of perforated window films—maintain visibility by keeping dirt, dust, and water out of the film’s holes,” she adds.
Recent advancements in ink sets change the way protective coatings are used, as they become more durable and lightfast. When additional protection isn’t necessary, overlaminates and coatings are used to change the finish, texture, and rigidity of a graphic, especially for specialty applications like floor graphics that require an anti-slip protection, or installations in venues prone to graffiti. Unique finishes—such as dry erase—are also available. “Many new coating and laminate formulations are continuing to be developed, mainly by advances in inks and inkjet coating technologies,” notes Alex Reid, product line manager, LexJet Corporation.
Mary Ann L. Kucera, market manager, MACtac Graphic Products, points out that UV inks are fairly tough and don’t usually require a protective coating or laminate. However, the surface of UV inks is typically not very attractive—especially when viewed up close. “Laminates and coatings continue to provide a decent, easily readable finish,” she adds.
Tony Caruso, regional sales, East Coast and Las Vegas, Advanced Greig Laminators, Inc., agrees, adding that one of the greatest advantages to laminating a UV-cured image is the elimination of bi-directional banding that quality laminates offer. “This provides a UV image with a clean, high-quality, professional look.”
The Best Fit
A number of factors come together to determine the best choice for overlaminate. Compatibility with underlying media is an important consideration that affects the adhesion and flexibility of the overall graphic. David Conrad, senior product manager—finishing, Neschen Americas, offers an example, “matching a vinyl-based banner substrate with a vinyl laminate ensures that as the banner contracts and expands, the film laminate does the same.”
There is also a choice between film and liquid coatings. Paul Roba, technical manager, North America, Avery Dennison Graphics, suggests that liquid coatings typically provide less UV protection, but can extend durability up to one to two extra years, depending on the coating. Most films provide UV stabilizers and superior UV resistance, extending ink performance for up to two to three additional years.
The usage of protective coatings and overlaminates on wide format graphics is largely dependent on its end use. The environment a graphic is placed in and its expected duration help determine which—if any—finish to choose. Steve Allard, product manger, FLEXcon, notes that floor graphics need a barrier film to protect the graphic from foot traffic, where something hanging on a wall or on a window or may not. This all depends on the method of print and where the graphics are placed.
Overall, graphics designed for use in medium- to long-term applications are generally best preserved with an accompanying overlaminate or clear coat. Those subject to harsh environmental conditions or abrasion require a protective coating as well. “In fact, recent conditions, such as acid dew and intense UV rays in the Western and Southern U.S., necessitated 3M to create a more durable overlaminate,” adds Tim Boxeth, business manager, 3M Graphics Market Center.
Protect & Serve
Protective film overlaminates and liquid coatings are an essential consideration, despite advancements in ink sets and underlying media durability. While limited applications, such as some short-term, indoor signage, are effective without a laminate, it is a critical element in other popular installations.