Like any ordinary printer, this machine ingests a blank page and spits it out covered in print. However, the difference is that this is a water jet printer.
Instead of ink, it uses only water - and, not only that, but the used paper fades back to white within a day, enabling it to be reused.
A team of chemists claims their water jet printer technology allows each page to be reprinted dozens of times – a cost-effective and eco-friendly option in a digital world that still relies heavily on hard copy.
“Several international statistics indicate that about 40 percent of office prints [are] taken to the waste paper basket after a single reading,” said Sean Xiao-An Zhang, chemistry professor at Jilin University in China, who oversaw work on the project.
The trick is in the paper, which is treated with a dye that colors when exposed to water, then disappears. The print fades away within about 22 hours at temperatures below 35 degrees Celsius as the water evaporates – quicker if exposed to heat, Zhang and a team wrote in a paper describing their invention in the journal Nature Communications.
The water jet printer's quality of print is clear, claim the designers - and the technology is said to be cheap.
“Based on 50 times of rewriting, the cost is only about 1 percent of the inkjet prints,” Zhang said in a video on the Nature website.
Even if each page were reused only a dozen times, the cost would still be about one-seventeenth of the inkjet version. It was also said that dye-treating the paper, of the type generally used for printing, added about five percent to its price, but this was more than compensated for by the saving on ink.
Crucially, though, the new method does not require a change to a specific water jet printer, but merely replacing the ink in the cartridge with water, using a syringe.
“Water is a renewable resource and obviously poses no risk to the environment,” the study said.
Previous work in the quest for a disappearing ink has tended to yield a low-contrast print, often at a high cost and sometimes using hazardous chemicals. However, this time, Zhang and his team used a previously little-studied dye compound called oxazolidine, which yielded a clear, blue print in less than a second after water was applied.
They have managed to create four water-printed colours for the water jet printer so far – blue, magenta, gold and purple – but can only print in one hue at a time, for now.
The next step is to improve both the resolution and the duration of the print. They are also working on a machine that will heat preprinted sheets of paper as they are fed into the machine, fading the pages instantaneously for reprinting.