Researchers from Shandong University in east China and the University of California, Riverside in the US have created paper which can stand to be re-printed on scores of times, reported the Daily Mail in the UK.
A sheet of the special paper can stand to be re-printed on up to 80 times, according to the report. The print material is ultraviolet, and the printed words and images disappear when the paper is heated to 120 degrees Celsius.
The core technology is said to be the ink, and any paper could be made re-printable if it can be safely heated to the right temperature.
The chemicals in the ink include Prussian blue and titanium dioxide. The blue component loses its colour when bombarded with electrons.
The special paper itself is blue before printing. When ultraviolet is used in the printing process, titanium dioxide in the chemical compound loses electrons, which are then obtained by the Prussian blue. Most of the sheet loses its blue colour, leaving behind words!
But the words on the paper are readable for a limited time only. After five days, the sheet of paper will have returned to its original blue colour and the words will be gone. The duration is even shorter if the paper is heated, even for only a few seconds.