“Unprinting” Technology Erases Text from Paper

Paper printing is an intrinsic part of life, all those tons of used paper go to waste eventually and there is always the need for more blank sheets in case someone wants to print something else.

A team of researchers from the University of Cambridge in England may just have a solution to this problem, at least as far as black text is concerned.

Essentially, they managed to create a so-called “unprinting” technology, which erases ink without damaging the paper.

To offer some context, a paper printer uses a laser to give “pixels” on a piece of paper a positive charge.

That causes negatively-charged toner particles to stick to those regions, leaving it to a heat source to fuse the toner and the paper.

The “unprinting” technology is quite different from this procedure, since it uses very short pulses of green laser light to vaporize the toner.

The pulses last for some picoseconds (a picosecond is a billionth of a millisecond) and green light is used because the black toner absorbs it while the cellulose fibers the paper is made of let it harmlessly pass through.

In addition to the convenience of reusing messed up sheets of paper, the major advantage of being able to erase printed text is the potential reduction in CO2 emissions, not to mention the lower need for cutting down trees.

Just making paper leads to millions of tons of CO2 emissions per year. Unprinting, in the worst case scenario, can produce half as much, though the ideal is 20%.

Unfortunately, since this is the first time this idea emerges in practical form, it will take quite a while for it to be put in use, probably years.

Also, consumer printers with this capability aren't bound to appear any time soon. It is more likely that the technology will be used only in the paper recycling industry for a while before that even becomes an option.

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