Tipp-ex for the modern world - just hit 'unprint' He added that he has now been approached by several commercial firms expressing interest in producing the first "unprint" devices. The researchers, whose work is published in the scientific 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 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. Dr Allwood and his colleagues estimate it would cost £19,000 to build a prototype unprinter but that the costs would come down as technology improves and it is commercialised. They calculate that reducing the cost to £16,000 would make the device valuable in most offices by reducing the need to buy paper. They also believe that it could 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 per cent.