The printer allows pages to be reprinted dozens of times.
The Age reported on the announcement from Jilin University in China, where scientists created a printer that uses water instead of ink, so that used paper “fades back to white within a day”, allowing reuse, and the “water-jet” technology, according to the scientists, “allows each page to be reprinted dozens of times”, saving money and the environment.
With this device, the secret behind the science is that the paper is treated “with an invisible dye that colours when exposed to water, then disappears”, with the printed image or text fading within 22 hours, at temperatures below 35 degrees Celsius. The image will fade quicker in high heat, and the researchers noted that the print “is clear” and the technology “is cheap”.
Sean Xiao-An Zhang, a chemistry professor at the university who has overseen the work, published a paper in Nature Communications on the discovery, adding: “Several international statistics indicate that about 40 per cent of office prints [are] taken to the waste paper basket after a single reading. Based on 50 times of rewriting, the cost [of the water-jet printer] is only about one percent of the inkjet prints.”
Zhang added that even if each pages was only reused 12 times, the cost would still be “about one-seventeenth of the inkjet version”, with dye-treating paper adding five percent to the price. He noted that “this is more than compensated for by the saving on ink”, with the site stating that “the new method does not require a change of printer, but merely replacing the ink in the cartridge with water, using a syringe”.
Previous attempts at creating such a printer have “tended to yield a low-contrast print”, The Age notes, “often at a high cost, and sometimes using hazardous chemicals”, but the new machine utilises a “previously little-studied dye compound” called oxazolidine, which creates a “clear, blue print in less than a second after water was applied”.
Four colours – blue, magenta, gold and purple – have been created at this point, though the machine can “only print in one […] at a time” at the moment, with the next step said to be “improv[ing] both the resolution and the duration of the print”, with the scientists also working on a device that will “heat preprinted sheets of paper as they are fed into the machine, fading the pages instantaneously for reprinting”.
Zhang commented that “water is a renewable resource and obviously poses no risk to the environment”, with the dyed paper said to be “very safe”, though the team is testing it with mice to “be sure”.