Chinese chemists pioneer water-jet printing

Most people are quite familiar with ink-jet printing. But a team of chemists from northeast China's Jilin University has recently attracted worldwide attention by inventing a water-jet printer.

Like any ordinary printer, the machine takes a blank page and covers it with print. But instead of ink, this printer uses water.

Although this does mean that the text will fade away within 22 hours of being printed, Professor Zhang Xiao'an, leader of the team, said that 40 percent of printed pages are thrown away after being read only once anyway. In addition, the printer can switch between water and ink in case the user wants a more permanent print.

What makes the technology work is the paper. But it's not some magic paper one might assume. Zhang said, "The paper we used in our experiments is a common type that people can get anywhere."

The trick is that the paper is treated with an invisible dye that becomes visible when exposed to water. The dye slowly fades over time, with higher temperatures causing it to fade more quickly.

Therefore, the water-jet printing allows one page to be reprinted dozens of times. It can help offices save money on paper.

Although chemical treating is involved, the cost is still relatively low. "According to our calculation, dye-treating the type of paper that is generally used for printing adds only five percent to the price. So it's very cheap," said Zhang.

What's more, "the significance of this technology lies in the fact that it's not only money-saving, but also environmentally friendly," said Zhang.

According to the official website of Ecology Global Network, nearly 4 billion trees or 35 percent of the total trees cut around the world are consumed by the paper industry on every continent. On the contrary, "water is a renewable resource and obviously poses no risk to the environment," as said in the team's study.

Zhang said toxicity tests conducted on animals showed that the treated paper is safe.

The chemists will continue their research to improve the quality and durability of the print. They also hope to work with interested companies in order to see the possibility of commercial production.

The research team previously published their achievement in the scientific journal "Nature Communications".