UV and LED-UV drying systems are changing the way we think about print finishes.
The LED-UV system allows printers to distance themselves from the old days of varnish effects that needed long drying times and required the use of powders. The UV process rapidly decreases drying time. Instead of drying by air and heat, inks are now cured by a chemical reaction called polymerization, which turns the wet UV ink into a solid when the ink passes by the UV lamps. This results in printed material that can be immediately moved to the finishing process.
That’s great news for print buyers, designers and brokers. Thanks to LED-UV curing systems, special effects can be done with much less risk than traditional methods.
What kind of special effects can be achieved with LED-UV?
High Gloss Finishes super glossy finishes are now done inline. No more farming the job out to a vendor. Saving time and money. One of the bigger complaints I've heard over the years is that regular varnish was not glossy enough. Led-UV coating puts an end to that.
Drip Off/Reticulated Finish this is achieved by using a matte primer in a printing unit, just as you would with a regular varnish. Then a flood gloss LED-UV coating is applied. The primer “reticulates” under the gloss coating leaving a uniform textured appearance. If you knock out areas of the matte primer plate the unprimed areas will have a high gloss appearance. Try to use design elements that can be effective at showing the special effect, I.E. don't use too much reticulation on the white parts of the paper. Rich colors will show the greatest effects.
Matte and Tactile Coatings think soft touch and pearlescent, combining aqueous coatings with LED-UV printing can yield stunning results.
Metallic and Opaque Inks such as white can be utilized for stand out effects because of the LED-UV curing method. These special inks are run in the first few units of the press then cured. This allows wet inks to be “trapped” over dry inks thereby enhancing the effect.
With LED-UV printing some traditional problems with special effects go away.
Set-Off because of instantaneous curing the inks are dry and won't get stuck together in the press pile.
Gloss Ghosting or Gas Ghosting with traditional printing, the varnish layer can be seen in solid ink areas on the other side of the sheet. This occurs because varnishes dry at different rates than ink, causing a "gassing out" chemical reaction.
Long Waits for Finishing are eliminated with LED-UV. All inks and varnishes are cured therefore dry and ready for handling.
A cost effective way to utilize LED-UV curing is to create traditional layers for the gloss and dull varnishes. The traditional process is to run the ink on a first pass then run the varnishes on a second pass through the press. This would give you the greatest effect for your varnish layers. LED-UV printing uses essentially the same technique, with one important difference. The color ink is cured and the varnishes are printed on dry ink. What in the traditional process takes two passes is achieved with LED-UV with one pass. All the while you still get all the advantages of LED-UV printing.
LED-UV drying systems are a newcomer to the printing field, especially to the U.S. market, but it has shown to be a force to be reckoned with. LED-UV curing is an energy saving and environmentally friendly process. Because of the low maintenance and ease of use more units are coming online daily. The application of special effects will let clever printers and designers lead the way with these exciting new techniques.