Saving Paper With “Unprinting” Technology

Remember the concept of the “paperless office”? Twenty years ago or more, we were told by futurists and technology experts that, not long in the future, we would work in offices mystically free of paper, every formerly papered process rendered digital. Then, there’s the depressing reality: Since the price of paper remains low and the price of high-quality printing has come down, we’re using more paper than ever.


Ironically, despite the ’70s being mostly non-digital, we used far less paper then, since making copies required going through the laborious and now antiquated process of mimeographing. Then came the 1980s, and we discovered how easy it was to put a piece of paper on a plate of glass, push a button and make a copy. Not long after, fax machines arrived in offices everywhere, churning out their shiny thermal paper. From there, paper use skyrocketed.

Printing today is still easy and relatively cheap, at least as far as cash is concerned, which is why few companies have any monetary incentive to cut down. It’s not so cheap when it comes to the environment, however.

While society has come a long way – fewer newspapers and magazines are printed in this digital age, the use of e-ticketing and digital coupons is on the rise and more companies are abandoning direct mail in favor of more modern electronic marketing media – we still waste far too much paper. Manufacturing paper is an incredibly messy business that produces millions of tons of carbon dioxide every year and uses so much water you’d think it was a typo – about 85 gallons of water to make only a little over 2 pounds of paper.

In fact, paper manufacturing is the single largest industrial user of water per pound of finished goods, according to the American Forest and Paper Association. It’s also the third-largest user of fossil fuels worldwide. About 35 percent of the world’s annual commercial wood harvest goes into paper-marking, and it takes two 15-year-old trees to make a single box of office paper. While paper recycling has helped us take a few baby steps toward sustainability, it’s by no means a cure for our paper use ills.

The U.S. leads the pack when it comes to paper waste. As a nation, we use a quarter of the world’s paper products. Each American uses about 750 pounds of paper per year, equal to a 100-foot tree with an 18-inch trunk. While we might like to think the paper we use is for noble purposes, the truth is pretty seedy: As a nation, we use about 68 million trees each year just to produce the nation’s junk mail of 17 billion catalogs and 65 billion pieces of direct mail.

During the last decade, technology has attempted to come up with ways to more easily reuse paper to address world’s paper waste problem, but until recently, these technologies were onerous and required special equipment, special ink and special paper (In other words, processes few people have the time or inclination to use).

Now, engineers at the University of Cambridge’s Low Carbon Materials Processing Group may be finally on to something significant. The group has developed an “unprinting” process that literally lifts the ink off printed paper, rendering it back to nearly the same condition it was in prior to printing. Though the Cambridge group isn’t the first to tinker with the “unprinting” process, they are the first to find a way to do so without damaging or discoloring the paper during the process. Moreover, their technology doesn’t require specially formulated toner or paper. The study was published in the Proceedings of the Royal Society this month.

The researchers’ goal is to allow paper to be reused on the spot instead of being recycled, incinerated or disposed of in landfill. The technology, once perfected and commercialized, could significantly reduce the environmental impact of paper production and use.

The unprinting process works sort of opposite to the way laser printing happens. During normal printing, a laser gives each pixel on a piece of paper a positive charge. After that, negatively charged toner particles are introduced, and they stick to the positively charged areas. A heat source is then applied to fuse the toner to the paper.

In the new Cambridge process, short laser pulses are used to erase words and images by heating the printing to a point where the ink literally vaporizes off the paper. These pulses are incredibly short: rather than seconds, they are measured in picoseconds (there are 1 billion picoseconds in a millisecond). Scientifically, the process is called “ablation.” While ink ablation on paper has been understood in theory for a long time, no one has ever been able to accomplish it without damaging the paper itself. To do this, the Cambridge team uses green laser light that is easily absorbed by dark toner, but passes harmlessly through the cellulose fibers that make up paper.

The researchers tested a series of 10 laser setups with the aid of the Bavarian Laser Centre, according to PC World. The range tested included ultraviolet, infra-red and visible lasers at different speeds, including ultrafast and long-pulsed lasers. The team ultimately settled on the green laser pulses, which removed all but the faintest ghost of the print. Subsequent testing with scanning electron microscopes and spectroscopy found that only a faint outline of erased print was left behind – apparently not enough to prevent reuse of the paper – and that tests for curling, bending and accelerated-aging on the “unprinted” paper found that it had not sustained any meaningful damage. In the team’s own words, the paper that had undergone the process was “comparable to blank unlasered paper.”

“When you fire the laser, it hits the thin toner layer and heats it up until the point that you vaporize it,” the team’s lead author, David Leal-Ayala, told BBC News. “Toner is mostly composed of carbon and a plastic polymer. It’s the polymer in the toner that is vaporized.”

Before (left) and after (right) examination of the "unprinted" paper. Source: University of Cambridge

As for this “vaporization,” the researchers used a gas extraction system to capture the nanoparticles and “mostly harmless” gases that were emitted by the unprinting process. What’s so groundbreaking about the process is that it works with commonly used papers and toner inks (the team used standard Canon copy paper with black HP LaserJet toner, like a million offices all over the world). It’s also far more eco-friendly than recycling – but it isn’t cheap. At least, it isn’t cheap right now. Researchers estimated that a commercial “unprinter” today could cost as much as £19,000, or more than $30,000. The trick will be to make the process sought after enough so the units can be produced more cost-effectively.

There are other processes that have attempted to make printed paper more on-the-spot recyclable (as opposed to shipping it off for large-scale recycling processes). Some of them have had success.

Japanese manufacturer Toshiba has been selling a special printer in concert with a toner called “e-blue,” which is a decolorable printing ink that can be rendered invisible by heat treatment. The system first prints the e-blue ink onto paper with a special printing unit, and then uses another dedicated unit called the “eraser” to remove the ink later. This allows companies to reuse paper, cut office waste and reduce business costs, the company says. In a manner similar to old thermal fax paper, the ink simply fades away off standard office paper under the right type of light, and the paper can be reused about five times. The products in Toshiba’s e-blue range, which was first introduced in 2003, include the decolorable toner itself, an erasing machine, a photoconductor unit and decolorable ink pen. (The technology developed by the Cambridge researchers, unlike the Toshiba process, can work with any common ink.) Here’s a demonstration of the process:

Xerox, for its part, has been offering what it calls the Xerox Inkless Printer, a printing technology that doesn’t actually require any ink. Instead, it uses a special reusable paper coated with a few micrometers of a “heliochromic” chemical material sensitive to UV light. In a manner somewhat similar to Toshiba’s solution, the Xerox technology can be printed and then erased – by applying another wavelength of UV light – over and over again, allowing for the paper to be reused repeatedly. However, the printed material the Xerox technology produces isn’t for the long term; thus far, it can last only about a day.

Until these processes are perfected and cost-effective (consider that the price of ordinary printer ink is sky-high…imagine what the ink for the Toshiba technology and the paper for the Xerox technology costs), it’s still going to be far cheaper to use recycled paper. Recycling paper is a positive step, as it uses between 60 percent and 64 percent less energy than manufacturing virgin timber paper, and recycling a single ton of paper can save about 7,000 gallons of water and enough energy to power the average U.S. home for six months, according to the Environmental Protection Agency. There’s certainly a lot of room for improvement in paper recycling – only 45 percent of paper is recycled in the U.S. and only 25 percent in Canada.

But while paper recycling is a good step, it’s not a perfect solution. The paper recycling process itself uses a lot of energy and resources such as fresh water, and emits copious amounts of carbon dioxide. And even recycled paper contains a significant amount of virgin wood pulp.

“When you recycle paper, you use a lot of resources,” said Leal-Ayala of the Cambridge team. “You use electricity, water and chemicals, and to be honest, when you print something, the only reason that you don’t reuse the paper is because there is print on it,” he told the LA Times.

For the Cambridge team, there’s a long road ahead to developing and commercializing their process. Though they’ve proved the technique works in a lab setting, they now need to develop a prototype device that would work in an office. They also need to secure patents for the technology.

“What we need to do now is find someone to build a prototype,” said Dr. Julian Allwood, leader of the Low Carbon Materials Processing Group, in a news release. “Thanks to hand-held scanners and laser-jet printers, the feasibility for reusing paper in the office is there.” (One wonders that given the associated security benefits of the technique – no shredding of sensitive documents required – if a few governments around the world might not make good backers of the technology.)

So what could the process save the world in terms of paper production resources? At the very least, the Cambridge team says its unprinting method emits half the carbon dioxide of paper recycling. In a best-case scenario, the team says, the process will be almost 20 times as efficient as recycling, saving not only trees and water, but an additional 50 to 80 percent in carbon emissions over recycling.

“This could represent a significant contribution towards the cause of reducing climate change emissions from paper manufacturing” said Allwood.

In the meantime, there are steps companies can take to cut down on paper use. A good start would be to find a “paper recycling promoter” in the company – someone who feels passionately about cutting down on paper use and is willing to take the time to craft in-office programs and processes to encourage the use of less paper and more recycling.

In addition, there are ways to cut down on the amount of unwanted marketing materials and junk mail that is sent to both your home and business. Using double-sided printers and copiers helps, as does buying a binding machine and repurposing used office paper into notepads. Turning tradition on its ear works, too: consider sending holiday e-cards instead of printed cards. (Greeting cards and other heavy paper stock items are responsible for an enormous percentage of the paper used worldwide each year.) Making use of electronic signature technology allows you to cut paper use on even contracts and other legal documents. Changing behaviors in the office helps as well, such as discontinuing the use of paper inter-office memos or printing e-mail and using document management software to store files digitally.

Once we’ve figured out a way to reuse paper, perhaps scientists can set their minds to finding a way to reuse the ink the process takes off the paper, saving us all from having to do the “cartridge shake dance” ritual to stave off having to replace the toner every two weeks.

 

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Comments:
  • March 28, 2012

    [...] Saving Paper With "Unprinting" Technology Saving Paper With "Unprinting" Technology Moreover, their technology doesn't require specially formulated toner or paper. The study was published in the Proceedings of the Royal Society this month. The researchers' goal is to allow paper to be reused on the spot instead of being recycled, … Read more on ThomasNet Industrial News Room [...]


  • March 31, 2012

    [...] Saving Paper With "Unprinting" TechnologyPrinting today is still easy and relatively cheap, at least as far as cash is concerned, which is why few companies have any monetary incentive to cut down. It's not so cheap when it comes to the environment, however. Engineers at the University of Cambridge may have a solution: The group has developed an "unprinting" process that literally lifts the ink off printed paper, rendering it back to … Read News [...]


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