Novel Printer Uses Water to Create Image

According to theage.com, scientists recently created a printer that uses only clear water, instead of ink, to form the image using ink jet nozzles. In this process, the printed image fades back to white within a day, allowing the paper substrate to be reused. As revealed, the secret lies in the special coated paper that contains an invisible dye. When that leuco (colorless) dye is exposed to water, the color becomes visible and then slowly disappears.

In a paper published in the Journal Nature Communications, Sean Xiao-An Zhang, a chemistry professor at Jilin University in China, added that the print fades away within about 22 hours at temperatures below 35ºC (95 ºF) as the water evaporates. When exposed to elevated temperatures, the print fades away faster. At 70ºC (158 ºF) the image disappears in 30 seconds.

Scientists recently worked out a method to create four water-printed colors—blue, magenta, gold and purple—which they can print one hue at a time. In the future, they plan to improve both the resolution and the duration of the visible dye image.

Zhang said that international statistics show 40% of office prints are thrown away after a single viewing. The inventors assert their “water-jet” technology is “a money- and tree-saving option in a digital world that still relies heavily on hard copy”.