Chemists pioneer water-jet printing

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

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

Although this means the text will fade within 22 hours of being printed, Zhang Xiao'an, professor and 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 as 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, 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 paper that is generally used for printing adds only 5 percent to the price. So it's very cheap," said Zhang.

What's more, this technology "is not only money-saving, but also environmentally friendly", Zhang added.

According to the Ecology Global Network, nearly 4 billion trees or 35 percent of the trees cut down around the world are consumed by the paper industry.

On the other hand, "water is a renewable resource and obviously poses no risk to the environment", according to 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 to explore the possibility of commercial production.

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