Soon, an 'unprinter' to remove ink from papers

Scientists claim to have developed a new technique that can remove ink from printed papers so they can be reused in printers and photocopiers. The technique, developed by a team at the University of Cambridge, uses short pulses of laser light to delete words and images printed on paper.

The laser vaporises the toner ink without damaging the paper and opens up the prospect of future computer printers and photocopiers having an "unprint" function to allow paper to be reused, the researchers claimed.

Dr. Julian Allwood, who led the research, said it could drastically reduce the number of trees cut down to produce paper and even provide a cheaper alternative to recycling.

"The process works on a wide range of toners. It does not damage the paper so the feasibility for reusing paper in the office is there," Dr Allwood was quoted as saying by The Sunday Telegraph.

He added that he has now been approached by several commercial firms expressing interest in producing the first "unprint" devices. The researchers, who detailed their work in the journal Proceedings of The Royal Society A, found they could remove toner ink from a range of printers and photocopiers by heating it with short pulses of laser light lasting for just four billionths of a second.

They found that while lasers that used ultraviolet light and infrared light were all effective at removing the ink, the most efficient was using a visible green laser.

This removed the ink without causing any physical damage to the paper or discolouration. Filters can be used to capture the vaporised ink, which is given off as a gas, they said. Dr Allwood and colleagues estimate it would cost 19,000 pounds to build a prototype unprinter but that the costs would come down as technology improves and it is commercialised.

They believe that reducing the cost would make the device valuable in most offices by reducing the need to buy paper. It could also be kinder to the environment by reducing the need to use as many chemicals to recycle paper and cutting carbon emissions savings of up to 79 percent, they noted.