Extremely high gloss UV, or ultraviolet, coatings offer more protection than either varnish or aqueous coatings. UV coatings are applied inline by printers or, more frequently, off-line by printers, finishers or converters. UV coatings are applied as a liquid, using a roller, screen or blanket, and then exposed to ultraviolet light to polymerize and harden the coating, with zero emissions.
The coatings can either be applied across the entire page or, while lacking the precision of a varnish, on a spot basis. The coatings are Available in a high gloss as well as matte, satin and wide variety of specialty finishes, including glitter and tints, and even different scents.
When first introduced, UV coatings were often perceived as murky and yellow. Those problems have been corrected, but the coatings still have other drawbacks. Like aqueous coatings, UV coatings are susceptible to chemical burning. UV coatings also are more likely to show fingerprints than either aqueous coatings or varnish, and some UV coatings can make paper difficult to fold. Dwell time, viscosity, temperature, the intensity of the UV light source and the interaction between the coating and the paper can all cause problems too. If conditions aren't right, the coating will not have a chance to spread evenly across the page before the coating is cured, and the finish can develop an "orange peel" look.
UV coatings also tend to accentuate the roughness of, or any defects in, the surface of the paper. Some printers insist that UV coatings require the use of coated paper stocks because uncoated papers allow the coating to sink into the sheet, leaving little of it on the surface. And in the past, most printers said that UV coatings should be used in conjunction with UV inks and that if conventional inks were used, they had to be wax free and allowed to dry completely before the coating was applied. However, new hybrid inks help reduce the potential for drying and surface problems.
UV Coating has 3 Different Types of Coating
- Matte Coating
- Gloss Coating
- Silky Coating