Overlaminates are becoming more and more widely used to protect images printed on a variety of substrates. Among those overlaminates are architectural finishes that add new life to signs and graphics that once had to stand on their own. Contrary to popular belief, overlaminates can be used on more products than ever, in new ways that one would not consider even a few short years ago. However, there are many PSPs that must learn to adapt the work to accommodate the use of overlaminates, particularly if a graphic requires a great deal of ink. High ink coverage can pose issues with overlaminates if the ink is solvent-based as it can cause delamination and other issues with the materials.
Jeff Stadelman, technical marketing manager of MACtac Graphic Products said that PSPs must be aware of how a piece is dried before lamination to prevent various issues.
“You don’t change the way you laminate them but you certainly change the way you dry them. If the inks are dried properly, lamination doesn’t make a big difference,” said Stadelman. “They start oversaturating it [the printed piece], and a lot of negative things can happen.”
Paul Roba technical manager, Avery Dennison North America for the Graphics and Reflective Solutions division, said, “High ink coverage has to be under the limits as described by the manufacturer, which typically is a 240 to 260 percent ink limit.”
Roba went on to say that the solvent in the ink can also cause the delamination of the product.
How does a PSP prepare a printed piece with high ink coverage for lamination? The answer is allowing for ample drying time.
Rick Nerenhausen of Lexjet stated that the amount of ink should not affect the way a product is laminated if the process is handled correctly.
“If a print material is properly profiled, high ink coverage shouldn’t change how you produce laminated graphics,” said Nerenhausen. “Wait 24 hours for the print to dry before you laminate, and then 24 hours to trim a pressure-sensitive laminate to let the adhesive cure for a solid bond. You can trim a thermal laminate once it cools off, usually just a few minutes after you laminate.”
Manufacturers of overlaminates echo Nerenhausen’s opinion. If laminating products with high levels of ink coverage, the key is to allow ample drying time before applying the laminate.
Roba said, “If you do get up to those higher levels you really have to ensure that you allow the graphics to cure for 24 hours by loosening the roll on end and allowing some air circulation. It’s all about the evacuation of the solvent from the media. If you don’t evacuate the solvent efficiently, the solvent will soften the vinyl; it will migrate through to the adhesive and cause the adhesive to become overly aggressive or, in some instances, it can cause the adhesive to fail prematurely.”
Stedelman added, “Make sure they have adequate dry time, which is 48 hours, open to the air so all that solvent gets out of there before they laminate or they are going to have a failed graphic.”
Judy Bellah of Clear Focus Imaging said, “One of the most common issues we see is not allowing enough time for the inks to dry and outgas before applying the overlaminate to the print. Graphics printed with high ink coverage using solvent-based inks, may require extra time to ensure adequate drying and outgassing.”
Exploring UV Protection
One of the benefits of using an overlaminate is to provide UV protection to the finished product. However, there seems to be some discrepancy between manufacturers and end users as to what UV protection really means.
Paul Roba said, “UV protection is the ability of a laminate to absorb some of the negative spectral output caused by the sun’s UV rays. Just as you get damage to your skin you get damage to your graphics and premature fading to your pigment in your inks.