The ability to print on to sheets of paper using water instead of ink is reported in Nature Communications this week. Printing typically involves large amounts of waste paper and reasonably expensive ink, often for documents that are only used for a brief time. The method reported in this research allows the paper to be reused numerous times, thus reducing waste, and could potentially have cheaper associated running costs.
Sean Xiao-An Zhang and co-workers treated papers with water responsive dyes. They found that simply by replacing the ink in an ink-jet printer with water they could then print as normal. The text could be erased and rewritten many times without a loss in quality. Given that many documents are printed for one-time reading, this method could offer a less wasteful alternative to traditional methods.