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A team at the University of Cambridge has developed a remarkable new technique that uses lasers to erase laser-printed paper, leaving pages clean, clear, undamaged, and ready to be reused. The technology has the potential to be even more eco-friendly than traditional paper recycling – scenarios suggest that it would produce at most “half the carbon emissions of recycling; best-case, unprinting is almost 20 times as efficient,” reports ExtremeTech.
Laser printing is a standard technology used in offices the world over that works by placing positively charged pixel regions onto paper, to which negatively charged toner sticks before it is heat sealed onto the surface. The University of Cambridge’s unprinting technology takes that sheet of paper and applies a “laser energy level that is high enough to ablate – or vaporize – the toner that at the same time is lower than the destruction threshold of the paper substrate,” according to New Scientist. The team’s lead author David Leal-Ayala added: “Toner is mostly composed of carbon and a plastic polymer. It’s the polymer in the toner that is vaporised.” So far, the scientists have found that the unprinting method can be used successfully on the same sheet of paper two or three times before the paper begins to yellow.
The unprinting team admit that they are not the first to come up with the idea of removing laser ink from paper: Toshiba has a proprietary “e-blue” unprinting method “which, like old thermal fax paper, fades under the right type of light,” reported Julian Allwood, who supervised the University of Cambridge’s project. Unlike the Toshiba technology, this laser driven method of unprinting could be applied to any standard printing technology, as soon as someone develops a way to integrate it into commercial printers. Allwood explained to gizmag: “What we need to do now is find someone to build a prototype… Thanks to low-energy laser scanners and laser-jet printers, the feasibility for reusing paper in the office is there.”