Group of DTG inks

Higher Quality Ink

Paul Boody

Fourth-Generation Inks Drive DTG Quality Improvements
New inks and better pre-treament advance the speed and quality of inkjet-to-garment printing. Direct-to-garment printing may this year begin to emerge from its infancy — at least relative to other decorating processes — and improved ink chemistry seems to be providing the momentum. 

Aug 29, 2008

Existing printer brands are expected to unveil upgrades and improvements at the fall trade shows, and a few new brands also will come to market. There will be improvements in production speed, automatic pretreatment units, RIPs, palettes, size of print area and other features.

But the big news this year in DTG is significant improvement in inks — the critical consumable that can make or break image quality and profit margins. In particular, a new generation — in many cases, the fourth generation — of white inks are performing much better than early formulations


A significant challenge for early adopters of DTG was printing bright and durable prints on dark garments. As in regular screen printing, colors pop off a dark shirt when the printer first lays down an underbase.

That base is even more critical in DTG, and it's really a two-step process. CMYK inks sprayed directly onto a dark shirt can literally sink into the fibers, ruining the shirt. To successfully inkjet print a dark shirt, you must first pretreat the garment with a proprietary chemical, hit it with a heat press and then lay down a solid layer of white ink as determined by your artwork.

Some decorators who jumped on DTG early struggled with white ink Clogging inkjet printheadslogging inkjet printheads. Many blamed the printers. Vendors preached the need for factory training and consistent machine maintenance. And some decorators with the right combination of printer, training and disciplined maintenance have been happily inkjet printing dark and light shirts since day one.

Other DTG printers found success with machines such as the Brother GT-541 that print only CMYK inks on light and white garments — avoiding the white ink issue all together.

garment_Printer_ink_qualityNEW DAY
A lot has changed in the white ink arena this year, and the clogging issue may at last fade away. The select few vendors who manufacture their own inks report they have their best-ever whites on the market. Almost all other DTG vendors use re-branded DuPont ink. Now in its fourth formulation, the new DuPont white seems to work great.

The common problem of early generations of white ink clogging printheads is as easy to understand as opening an old can of white house paint — it's hard to stir because of all the thick white stuff at the bottom of the can. That sludge is titanium dioxide (TI02), the pigment that puts the white in all white paint and all white ink.

So what's the problem? TI02 pigment particles are heavy compared to other pigments used in ink. That's why titanium dioxide settles to the bottom of ink containers and that's the genesis of printhead clogging.

New white inks on the market don't settle as fast. The new chemistry is proprietary to each ink factory, but a general description is that the titanium pigment particles are encapsulated in a way that keeps them suspended longer in the ink's aqueous (water) base.

"Manufacturers are trying to figure out ways to make the ink more encapsulated so that it doesn't settle. If the machine sits for a few days, the ink can settle in the heads," says Scott Fresener, president, U.S. Screen Print & Inkjet Technology, Tempe, Ariz. "It clogs around the capping station and gets a little gunky. It doesn't eat away the head, if you don't print for a week; that's a myth. But [the ink] is abrasive, so the machine is happier if you print every day."

Other anti-clogging techniques include flushing out the inks and turning off the printer if it won't be used regularly. Another technique is to leave your printer and computer running and install software that automatically runs a test print once every 12 to 24 hours.

Kornit is delighted with results produced by its Series 201 white inks, says Paul Borucki, vice president of North American operations, Kornit, Brown Deer, Wis. "It lets our clients print on delicate, pigment-dyed shirts without leaving any residual halo," he says. "Also, the white is very stretchable now and can print on a wider gamut of materials."

Dr. Chase Roh, president of AnaJet, Costa Mesa, Calif., says the company's new generation of inks includes a better-flowing white. "Color, overall, has improved," Roh says.

"The ink manufacturers put a lot of R&D money in," Fresener says. U.S. Screen's fourth-generation white ink delivers faster output. "It settles less and flows better, so you can print at a lower resolution and get more speed," he says "It covers better and it's more stretchable."

"People complain about their heads going out so fast. It's because the machines have a small squeegee that wipes off the head, but the ink is thick enough that it just sits there and crusts up," says Geoff Baxter, digital products manager, M&R Sales and Service, Glen Ellyn, Ill. "Our engineers are working on a feature that lets you push a button to eject the squeegee and wipe it off every night. In theory, this will substantially prolong head life."

DTG brand printers  the Kiosk II, HM1, Eclipse, Bullet and Xpress — feature automatic head-cleaning cycles and ink container agitation to avoid settling and clogging. "Issues of head clogging are minimal compared to a year ago,"  "White ink has improved a lot in the past year. [The new] generation of white ink is less prone to cracking and peeling, and that has become a little more tolerant of inconsistent pretreatment."

The Flexi-Jet printer by Belquette, Inc., Tampa, Fla., is one of the few machines designed so printheads and ink containers travel over a stationary palette.

Most printers in the $10,000-and-up price range are based on an Epson inkjet printer platform — specifically the Epson 4800 or the newer 4880 — the workhorse model that dominates commercial photography printing. Vendors in our industry use Epson printheads and some also use the rest of the mechanical platform and adapt that proven technology to garment printing. These printers typically have mechanics set the other way around — static printheads with a moving palette, usually via screw-drive.

Known for delivering a lot of features in an under-$20,000 model, the Flexi-Jet's design provides for natural ink agitation, as the printhead assembly slowly moves along the print area and then more quickly returns to home position.

Decorators who struggled with white ink in previous years and turned away from printing on darks may not be aware of ink chemistry advancements, says SWF East's Copeland. "They basically flushed out the white and never went back to it," he says. "We're trying to bring them back into the fold, letting them know the ink is better. And the key is, it's only going to keep getting better."

"The user has to accept the fact that there's a learning curve with printing on darks. Yes, it's just a printer, but it still takes some time to learn."

Brother Intl., has a significant share of the installed base of all inkjet garment printers and has achieved that via maverick strategy — no white ink. (Brother, U.S. Screen and DTG brand are probably the three best sellers in terms of installed units, though Kornit competes in its own class.) The Brother GT-541 uses only CMYK inks and has earned a reputation for reliability printing only on white and light shirts.

Long rumored to be working on a machine that will print dark garments, Brother won't come to market until it can be done "on a reliable platform," says Barry Silevitch, director of sales, Brother Intl., Lake Forest, Calif. "Brother's philosophy is that we're not going to put out a machine if it doesn't exhibit reliability. Right now, the ink has a ways to go."

Hirsch Intl. distributes the Mimaki GP-604, which uses proprietary textile pigment inks on whites and lights without pretreatment. (Hirsch also is among Kornit's distributors.) Richardson Supply, Columbus, Ohio, also carries the GP-604 and the GP-604D, which combines inks with a discharge solution. It bleaches organically dyed darks and sprays pigment inks all in one pass. (Hirsch does not carry the GP-604D.)

Another factor in print quality is pretreatment, an area that's also undergoing some serious improvements. Inkjet garment printing requires decorators to pretreat dark garments. To date, that has been as simple, and time-consuming, as using a spray bottle or an electric paint sprayer to apply an even coat of a proprietary chemical to the print area and then setting the fibers in a heat press. Too much or too little of the clear spray causes print problems.

U.S. Screen and Anajet were first to market automatic pretreatment units. Fresener says U.S. Screen is working on upgraded models, and Anajet's Dr. Roh indicated his brand also is fine-tuning the design of its pretreatment unit.

Look for other suppliers, including Belquette and M&R, to come to market with automatic pretreatment machines, promising to make direct-to-garment printing even more efficient and profitable. "This is just the tip of the iceberg," says M&R's Baxter.

Alone among all inkjet garment machines, Kornit printers incorporate a wetting agent spray in the actual print cycle.

Some vendors also recommend pretreatment for white or light shirts. While not required, it reportedly results in better-looking prints. "You don't have to pretreat whites, but it looks a whole lot better if you do," Baxter says. "It's probably 30% to 40% better."

U.S. Screen also introduced a proprietary pretreatment just for white and light shirts that is formulated not to yellow after exposure to sunlight (UV radiation). Without proper pretreatment, prints can look splotchy, Fresener says. "Some people say, 'I can't get a bright white.' That's because it wasn't pretreated properly," he explains. "It's like screen printing: Some people can do great prints, and others struggle with it."

Print quality isn't determined by ink alone, however. RIP software plays a big part in how much ink is laid down, and how it's laid down, greatly impacting the final print. "The RIP makes a lot of the difference," Fresener says. "We know what to do with a RIP, and how much ink to lay down." Almost every brand ships with its own RIP or one adapted from an off-the-shelf software.

With the iDot DK printer in development for two years, it's no surporse M&R custom-designed a proprietary RIP. "On the white shirt, it will dispense CMYK. On a black shirt, it runs white plus CMYK but no K," says Baxter. "This makes a much nicer print and potentially uses less ink."

The M&R RIP also lets users make some artwork adjustments normally done in graphics software such as Adobe Photoshop. That means there's no need to bounce a production file back and forth between the RIP and a graphics program. On the fly, the RIP also calculates print time and cost of each print. "It figures the amount of consumption of each color, and you put in the price of the ink," Baxter says. "It actually calculates the real cost. That's a neat feature."

The Brother GT-541 is one of the few, and perhaps the only, inkjet garment printer on the market that does not require a RIP. It loads a standard print driver into a computer's operating system the same way any desktop inkjet or laser printer would.

If you have been on the sidelines watching the inkjet garment printing business go through its growing pains, you might want to reconsider your position. The unique nature of inkjet garment printing can present opportunities for short run and one-off business you didn't have or couldn't take.

DTG is not necessarily right for every apparel decorating shop. To date, vendors report two sub-groups within apparel decorating that have found profit using inkjet garment printers: High-volume DTG-only operations (often new businesses and many selling direct via the Internet) and non-screen printers (embroidery and sign shops especially) that have been reluctant to invest the time, space and energy to do traditional screen printing. That's not to say that no traditional screen printers have gone DTG, just that embroiderers and all-DTG shops (especially startups) have been the best customers for inkjet garment printers.

The newest generation of white inks has resolved many of the questions about quality and printer maintenance. With new models coming online and new vendors entering the market, most decorators should be able to find a DTG solution that makes sense and makes money.

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