By Olivia Cahoon
Part 1 of 2
A printer configured with white ink offers print service providers (PSPs) a host of application options including the ability to print on black, clear, and metalized media. However, white ink does have its challenges. If not used regularly, the ink becomes clumpy and requires recirculation to avoid clogged printheads and if not done properly can result in purging. To combat this, wide format digital printer manufacturers offer device-specific configurations that keep white ink moving to minimize unnecessary waste.
Advancements in White Ink
Since its introduction, white ink has advanced to reduce printhead clogging, improve opacity, and maintain a bright white without yellowing. Traditionally, pigments for white ink were troublesome due to larger particles that increased the chance of clogging printheads, says Mark Goodearl, senior ink product manager, EFI. Additionally, opacity levels were low and unsuitable for applications that required little transparency.
“The developments in high-performance, highly opaque white inks for UV and LED imaging changed the scope of market applications customers could pursue with digital printing,” offers Goodearl. Today, multi-layer capabilities with white ink and digital printing expand compatible applications to premium quality point of purchase, day/night backlits, and graphics with white layers to create a motion effect on controllable LED light boxes.
Additionally, white ink formulations now offer added flexibility with the addition of improved RIP software, shares Larry Hettinger, product manager, wide format digital inks, graphic & industrial screen inks, graphic systems division, Fujifilm North America Corporation. This allows ink to stretch without peeling or cracking for use in window graphics, flexible packaging, and static clings.
A variety of applications benefit from white ink including those printed on clear, metalized, colored, or black media. According to Rick Mitchel, demonstration manager, swissQprint America, printing to black substrates has become frequently desired as well as applications with clear acrylics. This includes interior and exterior applications like environmental graphics, partitions, directional signage, menus, backlit signage, and drive-up menu boards. “White ink provides the ability to print a wide color gamut with a repeatable white point on a variety of colored and clear substrates that would otherwise need to be laminated or mounted,” he adds.
With white ink, PSPs can achieve special effects, especially with the use of metallics. Randy Paar, marketing manager, display graphics, Canon Solutions America, says it offers the ability to simulate printing with metallic inks by printing onto mirror/foil surfaced substrates. “White ink is used to either mask the foil, allowing the colored printing to look natural, or knocking out the white ink to simulate colored metallic effects since the colored inks are less opaque.”
Additionally, Paar explains that with select digital printers, white ink can be printed as a multi-level grayscale using variable droplets with the same detail potential as colored inks—allowing for creative, detailed white prints.
Tom Wittenberg, U.S. strategy, planning, and content lead, signage & décor, HP Inc., also believes white ink is a solution for achieving certain effects. For example, he says on aluminum composite sheets, white ink applied to a vacation image provides a shimmering effect on the water while also allowing the metal’s shine to be diluted so that surrounding images don’t shimmer as well.
White inks may also be used for layering effects or as an opaque base layer beneath color layers. “There are hundreds of different applications that could involve the use of white ink,” says Jay Roberts, product manager, UV printers, Roland DGA Corporation. With a flatbed printer, white ink is applicable to a variety of substrates including glass, metal, plastics, and acrylics, to create a vast array of durable, customized products.
In retail and marketing applications, white ink is applied as a spot color for text, logos, and brands. “With many modern printers that include white, there are options for using white as a full coat behind an image, or as a spot color for accent or other unique uses,” comments Dan Johansen, marketing manager, wide format solutions, Ricoh USA.
Roberts agrees, “the ability to apply a spot white to increase color vibrancy or to accent a logo makes this ink a useful printing tool.”
White Ink Challenges
The use of white ink is still relatively new, leading to an ineffective understanding of how to use it. PSPs handling white ink for the first time may feel overwhelmed. To understand how to best utilize white ink in production, Johansen recommends users experiment with a variety of methods and applications.
One of the largest challenges of white ink is keeping the pigment in suspension. “Most white pigment is titanium oxide—metal—which can damage the printheads if it separates out,” cautions Ken Parsley, product manager, UV/LED line of ValueJet printers, Mutoh America, Inc. To prevent damage to the printhead, he suggests agitating and recirculating white ink.
Special provisions are available to clean channels and minimize waste while offering the white opacity that PSPs desire. However, Parsley says this is a device-specific feature. “Ideally, white channels are always ready for use, with the ink being circulated or stimulated while dormant to keep the inks fresh and reduce potential for clogging.”
Devices where white ink must be added and/or removed can impact the other channels and be an issue for conversion time and cost/waste. To offset concerns for handling white inks, Johansen explains that many device manufacturers make ongoing improvements for white ink handling.
Ink recycling technology is one of several improvements that clean ink channels and minimize waste. According to Bill Brouhle, senior inkjet application specialist, Agfa Graphics, it enables operators to recycle all white ink out of the supply lines and put it back into the reservoir where it can be used for future jobs. “While at the same time, it fills the white printheads with a flush solution to put the white printheads in a safe hibernation state so that there will be no wasted ink, substrates, costly operator, and printer production time as well as expensive printheads,” he explains.
Other improvements include technology that keeps the pigment and carrier fluid in motion to reduce the opportunity for settling. Michael Maxwell, senior manager, Mimaki USA, Inc., says that combined with nozzle checking functions and automated cleanings, anti-settling technologies ensure the printer is ready to print and reduces costly maintenance and print quality errors often seen on other platforms. He adds, “white ink often has a stigma of settling and clogging easily, however, these concerns are easily addressed with superior chemistry and supportive functions.”
In May, HP announced its HP Latex R2000 Plus Printer. Waste between white ink jobs is prevented thanks to removable HP Thermal Inkjet printheads stored in an offline rotating chamber. Also, equipped with automatic maintenance, white ink experiences automation recirculation and nozzle checks.
A Bright Future
As white ink continues to achieve a brighter white with added opacity, visual advancements continue to grow. Christopher Dann, director of technical services, Durst Image Technology US LLC, says white ink is beginning to be used below colored ink to create a three-dimensional (3D) effect.
For example, Durst’s Hapt Print option applies several layers of white ink before finishing the image with standard process colors in one printing process. “The Hapt option allows users to create optical and haptic effects in imaging,” explains Dann. “Using ink to add depth and texture on a print is a unique, innovative feature.”
The Mimaki UCJV300-160 printer/cutter offers a similar feature with four layer printing to create transitional panels that move with the light source. The four layers—color, black, white, and color—allow for building layered transformative graphics for backlit applications.
Javier Mahmoud, VP of sales & marketing, CET Color, also sees PSPs using white ink to build up thickness in a print. For example, CET Color recently completed a sample on canvas foamboard where the client requested an oil painting appearance. “We substituted the black channel for white and printed white six times, which built up a nice layer, followed by printing the actual four-color image.” The final print resembled an oil painting with raised effects.
Thanks to advancements in chemical composition, PSPs can take advantage of white ink to produce creative effects. Part two of this series provides a roundup of available wide format printers that white ink channel options.
Jul2018, Digital Output