Here Come the Hybrids

Does inkjet technology complement screen printing? Or is inkjet destined to ultimately displace its analog cousin? 

Does inkjet technology complement screen printing? Or is inkjet destined to ultimately displace its analog cousin? 

We first pondered this question in the signage and display market. These are the applications from which screen printing itself emerged more than a century ago, and are also where wide-format inkjet first gained serious traction. From a traditionalist’s point of view, the test case must be considered cautionary. Inkjet eventually overtook screen printing in segments like retail graphics and outdoor advertising, and that’s no longer an opinion, but a fact.

Inkjet developers have long had their sights on what they believe to be bigger game in the textile industry. To this point, the results have been far less conclusive. Most studies estimate that inkjet’s share in textile printing, including garment decoration, is in the neighborhood of 4 percent today. However, many of the same market forces that worked in inkjet’s favor in the signage and graphics industry – shrinking run sizes, growing demand for customization, and increasing pressure on time to market, to name just a few – are every bit as relevant in garment decoration. And technology developers are beginning to respond with direct-to-garment (DTG) systems designed for significantly higher throughput.

Yet, just as higher-productivity DTG units are emerging, we’re also seeing a flurry of new hybrid machines that combine inkjet and screen printing in integrated production lines. This isn’t a new idea; the first hybrid machine, the Paradigm from Kornit, hit the market five years ago. Yet at the FESPA 2017 exhibition in Hamburg, Germany, six hybrid lines were shown, three of them for the first time. It’s difficult to ignore so much activity in such a short span of time.

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Whether hybrid printing leads to a different end game than the one we’ve witnessed in commercial graphics remains to be seen. But looking more closely at how DTG printing has developed in comparison with wide-format inkjet reveals a few clues.

Parallel Paths?
DTG inkjet technology emerged at the turn of the century, about a decade after it first appeared for commercial graphics. In both segments, the early inkjet devices initially met almost universal derision. Substrate options were limited. The inks were very expensive and didn’t meet all of the performance requirements of the finished product. And the units were painfully, almost comically pokey. No one took them seriously as production equipment, and in hindsight it’s not difficult to see why.

It took about two decades for wide-format inkjet to overtake screen printing’s share of the commercial graphics market. This happened through a series of breakthroughs that addressed each of inkjet’s technological shortcomings one by one. First came pigmented inks that enabled inkjet printed graphics to be used outdoors and in semi-permanent applications. Then solvent-based inks emerged with mechanical bonding properties that made print-receptive topcoats unnecessary on popular substrates and reduced the need for expensive lamination. UV inks followed, expanding the range of inkjet printable substrates and opening up a new category of flatbed machines that printed directly onto rigid materials. Finer-resolution inkjet heads were developed, and software advancements allowed OEMs to use more of them to enable faster print speeds. By this time, most commercial screen printers had added inkjet to their production in a serious way; it wasn’t just for samples and short runs any longer.

Then in 2007, the first wide-format inkjet lines that presented a serious alternative to screen printing emerged: the Onset from Inca Digital Printers and the M-Press from Agfa Graphics (first shown at FESPA 2005 through a remote video broadcast). These units, and more that followed from Durst, HP, EFI, and others, achieved much higher print speeds partly by using vast arrays of inkjet heads. They were expensive and slower than the inline multicolor screen presses that had become common in this segment by then, but by eliminating the time and associated costs of prepress and setup, they presented a realistic digital path to production-length printing for the first time. As ancillary technologies such as automated substrate handling systems and more robust print servers that could handle the vast amounts of data involved in high-speed printing became available, true technology substitution began.

Most industry observers agree that where inkjet development is concerned, garment decoration is about 10 years behind commercial graphics, which means 2017 could prove to be a pivotal year. Recently, two DTG systems have been introduced that aspire to be what the Onset and M-Press were in their segments a decade ago: the Vulcan from Kornit and the Kyo from Aeoon Technologies. Like their wide-format predecessors, both employ more printheads to help achieve higher print speeds, along with other productivity enhancements specific to this application. For example, although the machine designs are entirely different, both the Vulcan and the Kyo have more platens than standard DTG units; the Vulcan moves them through a sequential printing process that is analogous to the print stations of an automatic garment screen press.

Courtesy of MHM.

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While the appearance of these production-capable print lines echoes what occurred in commercial graphics, it’s important to note that inkjet faces a much different proposition in displacing the established technology this time. First, by the time that production wide-format systems were offered, most substrate-related challenges had been addressed, and that’s not yet so with DTG printing. Depending on their skill and the technology they use, not all DTG users in the field are able to get good results when printing synthetics. Most DTG work also requires the garment to be pretreated. (Kornit has addressed this on the Vulcan with an inline pretreatment station, while Aeoon offers an offline unit that can reportedly treat close to 1000 shirts per hour.)

Another key difference is that by the time wide-format inkjet technology developers set their sights on displacing screen printing, print buyers in segments like retail graphics had already been conditioned to design virtually all of their work in CMYK. In hindsight, although inline multicolor screen lines enabled printers to slash their turnaround times and remain competitive for many years longer than industry analysts had predicted, the shift to four-color process moved the battle against other printing processes to “enemy turf.” Screen printing’s unique ability to deliver an unlimited number of spot colors, dramatic clear coats, and special effects not reproducible by any other means was virtually forgotten by print buyers. Job quotes increasingly became a question of how many CMYK prints could be delivered and at what price, eventually leaving screen printing squeezed between inkjet at the low end and offset at the top.

In contrast, CMYK is not predominant in garment decoration; in fact, many shops choose to avoid true process-color screen printing altogether because of its difficulty. Instead, printers have put their energy into experimenting with special effects to create innovative looks that, in turn, resonate with consumers and command premium prices. That’s not to disparage the excellent imaging capabilities of today’s DTG technology – from a screen printer’s perspective, photorealism is itself a special effect, one they cannot come close to replicating with their traditional equipment.

But imagine what might have happened in commercial graphics if effects like DayGlo neons or sparkle metallics had been fashionable 10 years ago. The reality is that not all spot colors can be reproduced by CMYK, and many special effects are beyond the limits of the technology and likely to remain so, at least in a production setting. Neons, for example, may someday be achievable via inkjet, but that’s unlikely with dimensional effects such as high density.

Finally, garment decoration presents several unique challenges for inkjet where white ink is concerned. Printing white proved to be a hurdle for wide-format inkjet OEMs as well, and was an important milestone in the development of UV flatbed printers. But those devices didn’t have to achieve opacity on highly absorptive, often dark-colored substrates. Ironically, at roughly the same time that many screen printers were learning how to print thinner underbase whites to gain better control of their production and provide garments that were more comfortable to wear, DTG developers faced the opposite challenge: how to get adequate opacity on a dark background with a process that laid down just a fraction of the ink volume.

DTG technology has been capable of printing sufficiently opaque whites for many years now, without the stiff hand that screen printing can be prone to, especially when not done well. But it takes more ink, which brings time and expense into the equation. Many DTG developers employ multiple white printheads in order to achieve these thicker ink deposits faster, but on most systems, printing on dark garments still slows the process down. (The Vulcan is an exception, with quoted speeds of up to 250 garments per hour regardless of the shirt color.) And at any print speed, the additional ink increases the per-piece cost, which can be a limiting factor as the run sizes go up.

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Today’s Hybrids
The concept behind hybrid printing is simple and hasn’t fundamentally changed since the first Paradigm units were marketed five years ago. Instead of thinking in terms of one technology versus another, the idea is to use each process to its strengths. (Note: The charts accompanying this article provide basic specifications on the hybrid lines available in mid-2017. One additional manufacturer, the Italian company Tek-Ind, exhibited the Alfa Digital hybrid press at FESPA 2017, but did not respond to requests for information.)

Click the chart for a closer look.

All hybrid print lines include an inkjet station that takes the place of one of the printheads on a carousel or oval automatic screen press. These DTG stations print in CMYK only, not white; instead, jobs are configured so that one or more underbase colors are screen printed and flashed before the platens advance to the DTG unit. After the CMYK digital inks are printed, additional screens can be used to print highlight or spot colors, special-effect inks, adhesives for flock or foil application, and more. Then the finished shirts are put through a conveyor dryer, just as with a conventional screen line. Often, the line will be supplied with an interface that allows both the DTG and screen heads to be run from the master print controller.

Assuming that the underbase covers all of the design areas where the CMYK ink will be applied, hybrid printing eliminates the need to pretreat the garment; the print goes onto the underbase, not the garment itself. Printing the underbase via screen instead of DTG reduces ink costs and eliminates the speed of printing the white ink as a production consideration. It also reduces the amount of fluid being applied to the shirts, which can facilitate faster drying times. In most situations, at least four conventional screens are eliminated, further reducing costs and simplifying the job setup. The number of flash stations also goes down.

Hybrid printing presents an interesting combination of benefits that differ from those that commercial graphics printers considered when they faced the question of technology displacement. (Note: The M-Press was offered with an optional inline Thieme screen printing station; three such hybrid lines were reportedly installed in North America before the M-Press was discontinued in 2013.) But hybrid printing isn’t new; why is so much happening in this segment now?

The ability to combine finely detailed digital graphics with special effects such as the glitter on this shirt is unique to
hybrid printing. Courtesy of ROQ.

It’s tempting to chalk it up to the competition between the two technologies becoming more intense. To this point, DTG printing hasn’t been a real threat to screen printing. It has expanded the market for decorated apparel without eroding screen printing’s share of the pie. The Vulcan and Kyo (and other production-oriented DTG units that are sure to follow) clearly aim to change that dynamic and flip significant volumes of work that, until now, would have been screen printed, so it’s not surprising that vendors of conventional technology would respond.

But the reality is that these systems – the hybrids as well as the production-length DTG lines – have been in development for a long time. They all benefit from recent advancements that enable faster production speeds via inkjet. Manufacturers of hybrid systems are now quoting speeds as high as 700 shirts per hour, not as fast as a top-end automatic screen press running at full speed with no job changeovers, but at least three times faster than what was possible just a few years ago.

Still, the hybrid approach has limitations, the most obvious one being the analog underbase. Printing the white ink via screen may be more production-friendly, but it doesn’t lend itself to short runs or variable-data printing, applications that helped give rise to DTG in the first place. It also introduces another process with its own potential points of failure into the mix. Just as wide-format inkjet did in the commercial graphics market, DTG has brought an interesting variety of new players into garment decoration that aren’t screen printers and never were. Some of these producers are also in search of higher-productivity equipment, but it’s hard to see them bringing mesh and squeegees into their businesses.

The Possibilities
Perhaps the biggest advantage of hybrid printing is its flexibility. Thinking about how printers may employ the technology in the field brings some intriguing ideas to mind. For example, one approach to getting around the limitations of a common underbase would be to use the extra stations to load multiple screens with design variations that would be applied after the CMYK is printed. If a 2000-piece order involved five groups of 400 with different city names, the printer could load all five of the screens in a single setup and program the print controller accordingly. Printers could do the same thing by selling jobs with common designs and varying special effects, offering clients the ability to offer many more design options without making the jobs cumbersome for the printer to produce.

A similar idea would be to develop designs in which a common underbase could accommodate variable images. Picture a licensed sports design featuring a cap or helmet and text elements that could be universal – the year and the name of the league, for example. Instead of dropping in different text for each team, the design on the cap or helmet could be varied instead without requiring a change to the underbase.

Such ideas will require a new mindset throughout a printer’s organization. It goes beyond waiting for an order to come in that combines a photorealistic halftone with puff type in order to turn the DTG station on. Printers will need to look creatively at how the two technologies can be combined to produce garments that neither process can do alone, and then think strategically about how to bring those creations to market.

Printers will also need to think out of the box about how to reinvent their production strategies to truly leverage hybrid technology. Can they find ways to run jobs in parallel, with conventional orders running alongside DTG prints (with or without an underbase or post-print embellishments)? Would a second or third DTG head lead to exponential productivity gains if things like job staging and multiple load/unload stations could be worked out? The possibilities seem unlimited, and suggest a future that goes far beyond a simple choice between screen and inkjet printing.

Explore the rest of Screen Printing‘s October/November 2017 issue.