Soot from vehicle exhausts is being captured by a retrofit device and recycled into ink by a company in Bangalore.

The ink is not currently of sufficient quality to be used in printers but it is used by artists for painting and screen printing for use on bags and clothes.

BBC Click’s Spencer Kelly visits Graviky Labs, who invented the device and the ink, to find out more.

This programme was originally transmitted in March 2017.

See more at Click's website and @BBCClick.

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