Zink: Inkless Printing With Colorless Color

A magical new inkless printing technology has risen from Polaroid’s ashes

13 min read
Photo of Brian Busch [left], Stephen Herchen [center], and J.C. Van Dijk
Photo: Joshua Dalsimer

Major innovations in printing don’t come around very often. The last one was the inkjet printer, in 1976. And now there’s Zink, a full-color printing technology that does away with a messy, expensive annoyance that consumers have learned to hate: ink.

Zink’s first generation of printers was really only a novelty, spitting out prints measuring 2 by 3 inches (about 5 by 8 centimeters), but its second generation, which is only now rolling off assembly lines, allows formats of 4 by 6 inches (about 10 by 15 cm). That’s enough to crack the key home-printing market. And the technology is still very young.

The story of Zink is not just one of a unique technology. It’s about engineers and scientists pursuing a dream deep within a corporate research laboratory, long after most companies came to view research as a luxury they could do without. It’s a story of how those researchers stayed true to their dream, even as the venerable corporation whose 70-year-old brick walls sheltered them drifted into bankruptcy. The story even has a Madoff-like Ponzi scheme that sent key investors to prison. It truly is a modern fairy tale.

Once upon a time, in a 40-year-old company called Polaroid, a young Cambridge, Mass., chemist named Stephen Herchen began working on his first project. It was 1977, and instant photography was booming, led by Polaroid’s SX-70 camera, introduced in 1972. Herchen was one of 25 scientists and engineers working in a laboratory that focused on projects without timelines or product goals.

Herchen’s task was to take a look at a specific approach to instant photography that would get around a drawback of the SX-70 process, which was based on dyes that migrated up through an opaque screen to become visible. Because such diffusion is hard to control, the photographs had limits to their resolution. Herchen’s assignment was to find chemicals that started off colorless but could transform, with exposure to light, to the yellow, cyan, and magenta pigments necessary for a full-color photo. Because they’d be colorless, there’d be no need to hide them with a screen and therefore nothing through which they’d have to diffuse.

Colorless colors? It sounded like a task for Merlin. Herchen worked on the problem for about 10 years without solving it. Finally, he dropped the idea and turned to making better chemicals for traditional dye-diffusion films, contributing to the Spectra film introduced in 1986.

Then, in the 1990s, digital photography began eating away at the instant photography market, and Polaroid started scrambling. In the labs, researchers turned to developing printers for this new type of photography. They took two approaches—one intended to develop a high-speed thermal-transfer process for use in photo kiosks, code-named Opal, the other to create a portable printer, named Onyx, for consumers. Both were huge efforts and quickly became the main focus of the laboratories, with more than 100 researchers assigned to each.

Photos: Joshua Dalsimer
Secret Sauce: Zink’s magic starts in a chemistry lab, where scientists build unique molecules, lay them onto paper, and then apply heat to turn them from colorless to colorful.
Click image to make larger

Herchen became Polaroid’s vice president of R&D and chief technical officer in 2003, overseeing these projects. It wasn’t a happy time. Even though the photo-kiosk prototypes were well received, the collapse of instant photography dragged the company down. Polaroid cropped its staff even further, down from a peak of 20 000 to fewer than 6000.

Juan C. Van Dijk, a mechanical engineer who was working in product development at the time, recalls “trying to throw every kind of analog camera at the wall to see if something would stick. We had new high-end instant cameras. We had a low-end camera with a hand crank instead of a motor that was supposed to sell for US $9.99. We were really desperately trying to have something succeed.”

But the ones and zeros of digital photography trumped the chemistry of instant photography. In 2001, Polaroid filed for Chapter 11 bankruptcy.

Meanwhile, in the labs, the researchers on the Onyx portable printer began to think about a new approach—or rather an old one. Printing with the dye-transfer process, as used in commercial photo kiosks and portable photo printers, was slow and cumbersome: The print actually had to make four passes through the printer, one for each of the three colors and one for an overcoat. It had to stay precisely aligned as the motor moved it back and forth. And the printer needed yet another motor to move the ribbon when required. (Inkjet printing moves the printhead instead of the paper, also a complicated mechanical process.)

It occurred to everyone on the Onyx and Opal teams that the trouble lay in applying the different colors. What if the colors were somehow already in the paper, waiting to be turned on, the way phosphors are on a TV screen? It came back to the colorless-color problem that Herchen had tried and failed to solve. He’d been trying to create color that could be activated by light, but that hadn’t worked out—it was simply too difficult. But in the meantime, heat-activated color had become as common as a cash-register receipt. These devices used printheads full of tiny resistors that applied pulses of heat to paper, not so different from the printheads used in the dye-transfer device. No one was doing full-color photographic printing using heat-activated color, but that didn’t mean it wasn’t possible.

The single-color heat-sensitive papers already on the market used two colorless chemicals that formed a color when they merged. Single substances involved much simpler chemistry, which was important given the complexity already inherent in getting three colors in one paper. So the chemists in the company began developing single substances that were colorless in their solid crystalline state but intensely colored when melted out of crystal form, staying colored when cooled.

It took nearly three years to find chemicals that could produce yellow, cyan, and magenta. The next problem was how to control them; if you put all three colors in a single sheet of paper and used heat to activate all of them equally, you’d end up with mud.

It was time to get Polaroid’s electrical engineers and physicists involved. Brian Busch, a Ph.D. physicist who’d been working at the company for about four years, was the first to tackle the printhead problem. It was an exciting time, Busch recalls: “There’s the feeling of being the core of the team that’s working on the new thing, the future, the project that is going to save the company. And there was an incredible spirit of teamwork. I didn’t want to let down the chemists who had worked so hard to come up with these brilliant molecules that perform their magic so reliably. All I had to do was to get this obstreperous piece of hardware to produce some heat and melt the dye.”

it wasn’t all that simple. Busch and the two dozen engineers who worked with him on the hardware module needed to rethink the operation of thermal printheads. Existing thermal printers dealt with just one color at a time, so their resistors simply had to be hot or not. But the Onyx team needed to control three colors, and they intended to do it in a single 30-second pass across the printhead. Their idea was to fine-tune those colorless colors to activate at different temperatures, then precisely control the printhead to deliver the right amount of heat for the right amount of time for each of the 300 dots in each square inch of the print.


Busch calls it the “fried ice cream” approach, conceived by Polaroid researcher Stephen Telfer, now head of Zink’s chemistry and media development groups. “How do you melt a high-temperature molecule without melting a low-temperature one? With fried ice cream, you roll it in dough and throw it in really hot oil for a short amount of time. The coating fries without melting the ice cream because you’re hitting the shell with a high temperature, but the heat doesn’t get to the ice cream.” But if you want to melt the ice cream without cooking the dough, he says, just leave it on the counter overnight, and “the low temperature over a long time will melt the core.”

Fried ice cream was the answer to the colorless-color problem. The color closest to the surface—the one with just the right melting point turned out to be yellow—would have the highest melting point and the shortest pulse. That way the heat wouldn’t have time to migrate down to the next color (magenta), which has a medium melting point. The longest pulse would heat the third color (cyan), which was deepest down, but because it was at a low temperature, it wouldn’t affect the other two.

Busch and his colleagues worked on control electronics for the thermal printhead, precisely adjusting the time and temperature of the 200 million pulses of heat needed to make a 2- by 3-inch print. They came up with pulses of about half a millisecond for the yellow and about 10 ms for the cyan.

The chemists continued to tweak their colorless compounds, trying to adjust the melting temperatures to 200, 150, and 100 °C, low enough to protect the plastic coating but high enough to prevent the colors from being activated if the photo was left in the sun.

The team solved the puzzle by adapting the approach being used over in the Opal photo-kiosk project. The Opal researchers were also using heat, but instead of trying to melt the dyes directly, they embedded the dyes with solvents and used heat to activate the solvents. The Onyx team realized it was much easier to find a solvent that melts at the right temperature than to engineer a colorless molecule that responds to that temperature. The solvents then melt the colorless crystals into puddles of colorful ink.

On Christmas Eve 2001, it all came together. The group printed its first recognizable image using a thermal printhead wired to a field-programmable gate array chip. They’d proved the concept.

The reaction within Polaroid was mixed, recalls Van Dijk. “It was a disruptive technology—so disruptive that it would have killed camera sales. It would have killed instant film. So there was hesitation about going full speed ahead with it.”

Meanwhile, Polaroid’s business troubles continued. In July 2002, an investment firm, One Equity Partners, purchased the bankrupt company. The strategy was like buying a foreclosed house; the new owner would hang onto the company for a while, perhaps renovate it a little, and then try to sell it at a profit.

In April 2005, One Equity sold Polaroid to a Minnesota businessman, Thomas Petters, for an undisclosed amount. Petters immediately began using the Polaroid brand name on a line of digital cameras.

Petters wasn’t interested in continuing the Onyx research. “He was excited by the technology,” says Herchen. “We were able to do some pretty neat things with it, and it wasn’t that far off from being a product.” But continuing the research—the team then had 100 people on it—would have cost millions of dollars a year.

Petters gave the team six months to find a buyer or investor. A major inkjet-printer company was interested, and the team focused on making that acquisition happen. In May of 2005, though, the inkjet company backed out. Petters made it clear that he could not support the Onyx group after the end of June.

“It was time for a Hail Mary pass,” says Herchen. He and Busch, the physicist, got on a plane for Japan. Recalls Busch, “We packed our bags and a soldering iron and a couple of crude prototype printers, and in two weeks we did dozens of demos in Japan and China and Korea.”

“We put our paper into the cassette, and we could print images,” Herchen says. “They weren’t as high quality as they needed to be [for a commercial product], but they were very, very good, and they showed promise.”

Most of the executives they met with simply listened politely, then bowed farewell. “The companies basically said, ‘Yeah, okay, fine, come back to us when it’s really working,’” Busch says.

Until they got to Alps Electric.

Alps Electric Co., based in Tokyo, makes thermal print engines and printers for a number of well-known consumer electronics brands and ships thermal print engines to countless other printer manufacturers. By the mid-2000s, the 20-year-old technology was, by any definition, mature. The Alps executives may have reached the end of the road in optimizing it when Herchen and Busch landed on their doorstep.

“We took out our little printer—which was one of theirs—yanked out the ink ribbon cartridge, and said, ‘How would you like to see me print without that? Look at this space you could eliminate—all of the mechanisms and parts and motors and things that are used to move the ink ribbon—you’re not going to need that. You could make this half the size,’” Herchen told them.  “‘And there’s going to be no more of this four-pass process with each color printed in its own pass. We’re going to do it all in a single pass,’” a much faster proposition.

He hit the button and made the print. Within a week, Alps had signed on as a major strategic partner. It would develop and manufacture printheads and print engines using the Onyx technology and serve as an original equipment manufacturer to consumer-products manufacturers. Back in the United States, an investor named Robert Dean White offered to fund the spin-out of the Onyx team into a private company that would continue to develop the technology and manufacture and sell the paper. The team had beaten their deadline.

Back in Massachusetts, however, it wasn’t all champagne and flowers. For while White’s investment had managed to keep the project from drowning, it wasn’t going to be enough to support a team of 100 to profitability.

“It was a bit like Noah’s ark,” recalls Herchen. “We needed something of everything, some number of people who knew mechanical engineering, some who knew electrical engineering, firmware, software, molecular design, synthesis, physics, chemical engineering. We had to figure out the smallest number of people we could take that could cover all [that].”

He took 50 out of a staff of about 100. The choice was brutal, as was the announcement. “I had two meetings,” says Herchen, “one with a group of 50 telling them that we hoped they would come with us, and another with a group of 50 telling them they wouldn’t be able to do that. These were great people I’d worked with for years and years.” The researchers that wouldn’t be boarding the ark packed up their things and left that day. And on 1 October 2005, Zink Imaging incorporated.

Yes, that’s Zink. Not Onyx—that was just a code name—or Chromonyx, which briefly followed Onyx. And not iCMY, an attempt at merging i-coolness (the i stood for “inkless”) with an acronym for cyan, magenta, and yellow—which during a period of frustration came to mean “I can’t make yellow.” The development team had realized that the coolest thing about their technology was that it required no ink. So they named the technology Zero-ink, or Zink.

The new company gave an equity share to each of the 50 who made the leap from Polaroid. As part of the spin-out agreement with Polaroid, Zink took just about everything connected with the project, from the electron microscopes to the pencils on the desks, for a fraction of its value. It also walked away with a portfolio of 100-odd patents.

Already on the Market
Polaroid Pogo: (Left) This $200 camera has a built-in Zink printer.
Tomy Xiao: (Middle) This camera and printer package is available only in Japan.
Dell Wasabi:(Right) This $35 printer can receive images wirelessly.

With the money from White, some additional investment from Petters, and, in 2008, an infusion of funds from Mangrove Capital Partners, of Luxembourg, the group continued to develop their technology into a product. Both the chemistry and the electronics needed continual tweaking. Getting the color green to print cleanly, recalls Busch, was a particular nightmare, because it required activating the yellow top layer and the cyan bottom layer without affecting the magenta layer sandwiched in between. Researchers also had to engineer a top coating for the paper—one that would act as a lubricant when the paper ran through the printer, then as a protective sealant when the print was complete. And they needed to develop a system to make sure that when the software directed the printhead to produce a particular color, the right color would appear on the paper.

Their solution was to include a rough piece of paper, imprinted with a bar code, in every pack of paper. This addition cleans the pathway and enables the printer to calibrate itself, for each batch of paper has a slightly different sensitivity that must be compensated for to maintain color accuracy. The first generation of printer engines, with an image size of 2 by 3 inches (about 5 by 8 cm), came out early this year; the next generation, boasting images of 4 by 6 inches (about 10 by 15 cm), is due to ship in the fourth quarter of this year. The company is already testing prototypes of a version measuring 8 by 10 inches (about 20 by 25 cm). So far, Polaroid, Tomy, and Dell are selling products based on the Zink technology.

Zink’s success depends just as much on the paper as it does on the hardware. Of course, the hardware needs to be out there to sell the paper, but the paper is Zink’s core business. Initially, the Zink researchers made their paper, in sample quantities, on a pilot manufacturing line in the lab. But by November of 2005, they realized they needed a real manufacturing operation. Two months later, they picked one up for a song. William Keating, a Zink senior vice president, heard that Konica Minolta Holdings, a joint venture that made paper for professional photo minilabs, was getting out of the business and closing its Whitsett, N.C., factory.

“We asked them to stop the auction and give us the time to see if this was a fit for us,” says Wendy Caswell, now the chairman and CEO of Zink. It was. Zink purchased the factory and all the equipment in it at what Caswell considers an incredible bargain. “It was a win-win. They didn’t have to lay their people off, which mattered to them, and Zink acquired a state-of-the-art manufacturing facility and a team to operate the plant.”

By September of 2008, things were running pretty smoothly. Zink had solid financing from an established venture firm. It had its first consumer-electronics partners ready to introduce products in early 2009. It had been producing paper for several months.

And then, on 3 October, White and Petters, Zink’s original investors—and at that time, board members—were arrested in Minnesota, charged with mail fraud, wire fraud, money laundering, and obstruction of justice in a scheme that had defrauded investors of some $3.65 billion. (Bernard Madoff’s Ponzi scheme would grab even bigger headlines two months later.) At press time, Petters was expected to go on trial in October. White pleaded guilty and faces up to 22 years in jail.

Caswell heard of the arrest on the morning news. She spent the day working with the Mangrove team, and by that evening, Petters and White were off the Zink board and the company was on its way to being restructured to dilute the pair’s ownership to an insignificant amount, insuring that Zink and its assets would not be affected by any legal proceedings. It’s not exactly clear where the money the two invested into Zink came from, but Caswell says it doesn’t matter to the company’s future.

Today Alps is producing Zink print engines. Foxconn Technology Group and Lite-On Technology Corp., both of Taipei, Taiwan, are building Zink-based products for major consumer-products companies. Four Zink products are already on the market—the Polaroid PoGo printer, the Polaroid PoGo camera, the Tomy Xiao camera, and the Dell Wasabi printer, ranging in price from $35 for stand-alone printers to $200 for an integrated camera printer. Zink paper sells for about 30 cents a sheet. The company expects to sell to both consumers and businesses. On the consumer side are all the traditional users of photography. On the commercial side are insurance agents and police, who need to staple a photograph to a report instantly, fashion photographers, and decorators, as well as photo kiosks, medical offices (for color-coded labels), and commercial signage (Zink’s images are water-resistant).

And the Zink technology is catching on among artists, much as the old Polaroid technology did, back in the day, and for the same reason—you can alter the colors while the photo is developing.

The company, now based in Bedford, Mass., has 100 employees. At this writing, 49 of the original 50 who left Polaroid remain; the 50th left to do missionary work in Bolivia. The company is winding up a final round of venture funding and expects to be operating in the black by early 2010.

People, Caswell says, have “an inherent hatred of ink. ‘Ink costs so much,’ they say. ‘It runs out at the worst time possible. It’s messy. The jets clog. Then I have to blow through ink to unclog them.’ The technology has decades to go; we don’t know today all of the applications for it.”

Perhaps on the moon or Mars—zero-ink printers work just fine in zero gravity.

This article originally appeared in print as “Zink: A Modern Fairy Tale.”

For more on Zink, see “Behind the Scenes at Zink: Where Color Magic Happens.”

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