Remember that cool pen to use in a school that used light to read invisible messages? That’s no longer cool. There is a whole new way to write and read invisible messages and you can use it as and when you want.
The method was developed by researchers in China. They use water to print messages on paper mixed with manganese-containing chemicals. The message, not seen to the naked eye, can be read by shining UV light on the paper.
A hairdryer’s hot air can be used to erase the message according to the researchers. Once the message has been seen and the task is completed, it is easy to ensure it does not fall into the wrong hands.
Rather than destroying the message (forget even self-destructing), blow-drying the paper for 15-30 seconds not only erases the message but the paper can be used again for printing.
“The rewritable facility largely decreases the cost. The cost per print will be set around RMB0.014 ($0.002),” explained senior author Dr. Qiang Zhao in a statement.
“Most fluorescent security inks available in the market used to keep confidential information are not even friends for the environment and it cannot be erased. The paper is merely a disposable recording medium.”
Environmental footprints may not be ide for those sending clandestine messages, but Zhao is confident it’s not just the ink that does well on this score. The manganese coating is extremely low in impact, including in toxicity for those handling the paper.
In extreme cases, Zhao has taken his own backups, mixing the ideal coating with magnesium chloride and magnesium bromide inks that are cannot be seen under both sunlight and UV. In these scenarios, only photoluminescence lifetime imaging, which is difficult to get, will reveal the hidden text.
Nothing has been disclosed yet about its commercial release.