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Liquid Courage: Coating Technology for Print Protection

(February 2008) posted on Wed Feb 13, 2008

Liquid lamination offers graphics producers the ability to protect prints at a competitive cost and minimize waste and labor in finishing. Read on to find out more about the technology and the applications for which it is suited.

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By Ben P. Rosenfield

The laminator has become a standard piece of finishing equipment for graphics screen printers who have added wide-format inkjets to their imaging arsenals. Its primary purpose is to place a barrier between a printed graphic and the wear it will inevitably experience in use. Laminators in the graphics industry are generally thought of as machines that apply films to protect graphics from the elements, damage from scratches and abrasions, exposure to harsh chemicals, and more. But laminators also can take another form, one in which they apply protective liquid coatings. Liquid laminating technology is the focus of this article, which will look at the equipment, coating types, applications, and benefits associated with this finishing process.


The liquid laminator

The liquid laminator is essentially a coating machine. At the most basic level, printed graphics are loaded in the device, coated, and then unloaded. Intermediate and final steps in the laminating process vary according to the type of coating in use, which can be UV curable, water based, or solvent based. For example, media treated with a UV coating would pass through a curing station before it could be unloaded, while a substrate coated with a water-based formulation, depending on the laminator's level of automation, many travel the course of an infrared drying chamber to hasten the drying process.

Liquid laminators are available in a variety of configurations and sizes to suit a wide range of applications. Manually operated and automatic units are available, as are flatbed and roll-fed types (Figure 1). UV laminators are typically reverse-roll, three-roll systems. Water-based laminators generally flood-coat the substrate and then employ a Meyer bar, also known as a wire-round metering rod, to reduce the coating's thickness to the appropriate level. A squeegee or similar device removes the coating from the back side of the substrate.

"It's not roller coating, it's actually wiping," says Ike Harris, president of Daige, Inc. "It's a special rod that's used in labs when they want precision coating. It's also used in manual and big roll-to-roll machines to apply water-based coatings. It wipes off the image side and leaves a very smooth, even coating."


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