QA: Curing UV Printing

Don’t you just love when you buy the latest and greatest new piece of technology at that jaw-dropping price tag? Sure, it may be pricey, but you’re as giddy as a little school girl because this gizmo can do everything short of sending you to the moon. Then, it turns out —it was the biggest piece of junk you ever bought. It sounded good on paper, but the technology just wasn’t there yet. Then a couple of years passes, and not only does the price tag significantly come down, but the new models actually work!

UV-curable flatbed printing has come a long way. After working through a few kinks, UV-curable flatbed printers now offer affordable, high-quality images at that speedy advertised advantage. Throw in its popular “green” effects, and you have a printing trend on the rise.

Q: How do UV-curable inks work versus solvent inks?

A: Perhaps you’ve heard the term “instaneous cure” inks? This is the precise difference between the UV-curable and solvent ink families. UV-curable inks are “cured” once they are exposed to wavelengths of UV light. The ink consists of a photoinitiator, and when exposed to the UV light, it undergoes a chemical process that transforms the ink into a solid film that tightly adheres directly onto the substrate’s surface. This all happens within a fraction of a second. Contrarily, solvent inks dry based on a slower evaporative process, triggered by a separate or sometimes attached heater, which burns the ink into the surface. The solvent then evaporates. Because solvent inks literally embed the image into the media, the resulting image is scratch and water resistance with long-term outdoor durability.

Q: What are the advantages and drawbacks of using a UV-curable flatbed printer versus a solvent printer?

A: As with any application, there are advantages to using both UV-curable flatbed and solvent printers. While the flatbed market is dominated by UV-curable printers, there have been issues with the adhesion and flexibility properties of the UV-curable inks, but this continues to improve with evolving technology. Solvent ink printers, however, are ideal for flexible applications, such as vehicle and building wraps, because they have high rates of coverage and durability.Of course, UV’s instant curing is a huge advantage. Shops can crank out projects without the extra labor and time waste that it takes to dry a solvent printed job. As they say, “Time is money.”

Q: What are the best types of jobs/applications for using a UV-curable flatbed printer?

A: UV-curable flatbed printers find their distinctive niche in rigid substrate printing because solvent printers do not have this capability. Typically, UV-curable flatbeds can print onto rigid substrates that measure up to 2" thick. Also, given UV-curable ink’s vivid colors and hardness qualities, it’s especially ideal for outdoor signage and has less substrate limitations than solvent printers. That said, UV-curable ink is also popular for producing indoor POP displays.

Q: What factors should you use to determine if purchasing a UV-curable flatbed printer is the right investment for you?

A: When considering purchasing a UV-curable flatbed printer, shops should carefully consider the types of planned applications over the next five years. Start by asking a few basic questions. How well does the unit handle those applications? What are your capacity needs now and in the future? What is your budget? What are your floor space limitations, if any? What post-print processing will you need to do, and how well does the finished graphic handle those processes? Besides intended applications, it’s recommended that shops examine the product acquisition price, the cost per copy, image quality, durability, environmental health and safety requirements, and the level of service and support provided by the vendor.

Q: Why are UV-curable flatbed printers more environmentally friendly?

A: When solvent ink evaporates, it releases harmful volatile organic compounds into the atmosphere; however, UV-curable ink is based on a 100 percent solid ink system that is instantly cured into a film without the evaporative drying step. Besides, UV-curable ink contains little or no solvent. As an added bonus, not only is this safer for the environment, but it’s also safer for your employees. UV-curable ink reduces worker exposure to the dangerous VOCs, and there is no need for a ventilation system that is required for solvent printers.

Q: Why is lamination unnecessary when printing with a UV-curable flatbed printer? What instances would you want to laminate?

A: For certain applications, especially indoor signage, laminate typically is unneeded. The ink itself polymerizes during the curing process, essentially turning the ink into a thin plastic layer, and that extra layer of protection doubles the colorfastness. There are certain cases, however, when lamination is recommended, especially in outdoor applications when it is directly exposed to sunlight. Also, lamination is often used to shield the substrate from environmental elements and adds an extra layer of protection to the ink film. For the best finish, use liquid laminates on rigid substrates.

Q: What other machines should you consider for purchase with your UV-curable flatbed printer? Why are they beneficial?

A: If you plan on investing in a UV-curable flatbed printer, you should include a digital cutting system in your venture so the rigid media can be easily routed or cut for contoured finishing. This system greatly reduces the amount of labor and waste. Improved turnaround time will make your shop more efficient. Overall, a digital cutting system improves the end quality and consistency. If you’re not ready for that type of investment, rigid board finishing can be accomplished with an A frame or other straight-line cutter.

Q: What qualities of the substrate can affect the print job of UV-curable flatbed printers?

A: The age of a substrate, especially when using styrene, can affect adhesion results. Over time, the dyne level of the styrene can change, resulting in a reduced level of ink adhesion, but using freshly manufactured media fixes this problem. It’s particularly important to pay attention to this issue because adhesion quality tends to be a problem when working with UV-curable printers.

Q: How has UV-curable technology and quality improved since UV-curable printers were first introduced?

A: When UV-curable printers first hit the market, they produced a low resolution at a sluggish speed, but improvements in ink technology are yielding significant advances. Photorealistic 1440 dpi print quality and a wider color gamut with richer hues are now available. Plus, these quality images have a gloss finish option—a quality once unique to solvent printing. Manufacturers continue to improve current UV lamp performance and are developing new technologies, such as high intensity LED lamps that reduce power requirements, eliminate radiant heat and greatly increase lamp life. While this is not yet broadly adopted, this technology shows promise as ink formulations are perfected to effectively cure at these light levels and wavelengths. Ink formulations are also improving to provide better outdoor durability, flexibility and adhesion.

Q: How has the market changed regarding value and affordability of UV-curable printers over the years?

A: Even five short years ago, UV-curable printers were expensive, of marginal quality and slow, but that is all changing. We now see the fastest printers on the market employing UV-curing technology. Since UV-curable printers have been reintroduced as a mainstream, affordable technology, the market has expanded, and even small businesses can take advantage of the high-quality, cost-effective printers. In a tight economy, UV-curable printers are helping small businesses finding cost savings and labor reduction, while saving on their bottom line. The UV-curable printing market can expect to see its greatest growth producing outdoor rigid signs, because this business segment typically is the most difficult and expensive to produce. Small sign shops now have the opportunity to capitalize on these pricey, upcoming market trends.

Special thanks to these contributors:
AgfaMike White, Wide Format Manager, Industrial Inkjet Systems
DurstChristopher Howard, Vice President of Sales and Marketing
Fujifilm SericolTerry Amerine, Segment Manager – Wide Format
HPGrad Rosenbaum, Vice President, North American Signage Business
GandInnovationsTom Reilly, Vice President of Marketing and Advertising
GCCLisa Hsu, Senior Specialist at Inkjet Product Line
GerberPeter Marchi, Executive Director of Marketing
OcéRandy Paar, Display Graphics Product Manager