Zhang and his colleagues developed a special coating on the paper that responds to the water. So far, they have been able to print various Chinese and English characters using blue, magenta, gold and purple colors, using water as a key that activates the dye molecule. The next step is to combine colors to get black, Zhang said.
The possibility of reusing paper instead of throwing it away is intriguing, according to Kira Barton, professor of mechanical engineering at the University of Michigan and an expert in high-performance printing technology.
"Going toward more sustainable techniques of printing is helpful and beneficial," Barton said. "It would be interesting to quantify the quality and regularity and repeatability you could get before you see degradation. For standard typing, I think it's an interesting idea and something worth exploring."
Zhang said that he foresees advances in printing technology that would allow consumers to have entire newspapers or magazines printed at home with paper that could be recycled over and over again. Based on 10 uses per sheet of water-jet paper, Zhang estimates the cost at one-seventeenth the current price of inkjet printing.