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People will lather gallons of sunscreen on themselves during summer to protect themselves from ultraviolet rays. The cause of that redness that can make people miserable—ultraviolet radiation—is one reason overlaminates are such a useful part of the wide-format printers' tools.
An overlaminate, in its simplest term, is a transparent film used for graphic protection over other graphics such as floor, fleet, or outdoor graphics. Overlaminates can not only lengthen print life in the sun by acting as a "print sunscreen," but also have the capability to protect prints from humidity and the weather by sealing the print more securely. In floor graphic applications, overlaminates protect from scuffing and slip resistance. Specialty or performance overlaminates can also provide graffiti protection and easier cleaning, according to Jared Johnson, marketing manager, 3M Graphics Market Center.
"Overlaminates are generally required for digitally printed graphics for exterior applications," said Johnson. "Most overlaminates have UV inhibitors in them to help extend the life of the graphic, and reduce fading of the inks. However, an overlaminate can only extend the life of the inks, so the ink formation is very important to the overall life of the graphic."
Remember the old peeling graphics on billboards alongside roadways? In almost any metropolitan area subject to dust, smog, and weather, you will see examples of vivid graphics kept that way for years because of overlaminates.
"Overlaminates really give you a chance to extend the life of your graphics," said Curt Hess, associate digital product manager of the Avery Dennison Graphics & Reflective Products Division. "That's the key to them right now. Most of the inks that are unprotected [will last] about two years or three years, depending on the OEM. By putting an overlaminate on it, you can take it out to five years now."
In today's workflow, sometimes overlaminates and overmasks are combined for processing in one step, according to Hess. If 10 images are the same, the printer will load the printed roll onto a large sealing laminator for roll-to-roll lamination, "and they'll just go from printed roll to overlaminate roll and do the whole thing in one shot."
Ink Check Important
Ink selection is important for the warranty to be extended by overlaminate manufacturers. For example, Karen Buckleman, product specialist, laminates and adhesives, Neschen Americas, stated the guarantee for SEAL overlaminate products at Neschen Americas requires pigmented ink, allowance of adequate drying time before laminating (24 hours or more) and proper preparation of the graphic prior to mounting.
Drying a print adequately lowers the potential for waste. Solvent inks sometimes have sheen and are still tacky to the touch if not adequately dried before overlaminates are applied, Hess said. If there isn't adequate drying, overlaminated graphics may peel into layers because of the interaction of the solvent inks and the media.
Often inks are specified. Avery Dennison requires approved inks for its warranty for eco-solvent inks in a graphic and that only approved and tested third-party ink will receive a warranty.
"There are a lot of third-party inks out there," Hess said, "and I'm not saying whether they're bad or not—but if neither we nor anyone else has had a chance to test them, there's no telling what will happen with it when you overlaminate."
Warranties are sometimes given for products outside those made by the OEM furnishing the overlaminate. For example, 3M offers a performance guarantee for replacement of the film and overlaminate if there is failure when inks from a wide list of OEMs are used with 3M base films and overlaminates.
"We also test these combinations of inks with our films and overlaminates," Johnson said, "but because we have little if any control over the development and manufacture of these inks, we warrant only the replacement of the film and overlaminate if there is a film or overlaminate failure during the period of the warranty. Fading or other ink appearance issues are not a part of the 3M Performance Guarantee."
Adding Pop, Vibrancy, and Depth
Overlaminates can also add allure, giving a graphic more depth, richness of color, and texture.
"Overlaminates can make an ordinary graphic extraordinary," Buckleman said. "One example would be using a gloss or luster overlaminate over a color graphic. The highly reflective surface intensifies the colors and makes them pop. Also, overlaminates can be made in a wide variety of textures for a wide variety of uses. This instantly increases the value of the graphic while customizing it for any number of specific uses."
The thicker construction of overlaminates allow easier application for fleet graphics on highly-contoured vehicles, according to Johnson, and make a more "paint like" finish common on vehicles.
Said Hess: "You can take an image that looks a little flat on a map media, and if you put that gloss overlaminate on it, it absolutely makes it stand out."
Overlaminates have to be used wisely. Matte overlaminates are best for use with text displayed in trade shows. The glare of lights on a glossy overlaminate would make text hard to read and graphics hard to view.
"The same holds true with outdoor applications, as well," Hess said, "if you think of the Fourth of July parade and a banner is hanging up or is stretched across the road, more times than not, you see a glossy overlaminate on that and more times than not, you can't read it, either...You really need to think about the application and what you're doing with it and what the expectations are."
Neal McChristy welcomes feedback about the articles he writes for the wide-format industry and would like to have readers suggest future topics. Contact him at nmcchristy@cox.net or visit his website at www.ezsnailmail.com.
author: BY NEAL MCCHRISTY