Together with steel, cement, aluminium and plastic, paper is one of the five key engineering materials of the modern world. Developing technologies to use paper more efficiently can deliver tremendous reductions in carbon emissions.

A technology that borders science-fiction was developed in the Use Less Group at the start of the 2010s: paper unprinting. The concept is simple: removing ink from paper using a laser. Thanks to laser irradiation, printed toner evaporates without damaging the paper fibres. The implementation is a little trickier, and former PhD student and postdoc Dr David Leal Ayala performed many experiments to find the optimal conditions to unprint: the results were published in the Proceedings of the Royal Society A.

The idea was so appealing that in 2014 David founded a start-up called Reduse, based at the ideaSpace City site, which showed great potential. It was named the winner at the Venture Competition ceremony for the UK’s top climate start-ups organised by Climate-KIC (Knowledge and Innovation Community) UK, and Cambridge Enterprise supported it with a seed fund investment in 2015. The promise is that of a device that fits into commercial printers and allows uprinting paper with the same speed and ease of printing it.

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