Boffins in New Zealand have worked out a way to make paper which is magnetic, conducts electricity and glows under ultraviolet light.

By coating the paper with nanoparticles, Aaron Small and Jim Johnston at Victoria University have made paper which can create labels that can change colour when the use-by-date has expired.

Spraying the nanoparticles on card could provide a cheaper alternative to metals, such as copper, which are commonly used to shield equipment sensitive to electromagnetic radiation such as cellular and wireless network frequencies. It can also be used to conduct electricity and glow when exposed to ultraviolet light making it useful for secret security labels.

There is more to the story than the technology. New Zealand exports a huge amount of paper products to the rest of the world, using trees made from renewable state forests. The country is always looking to add value to its products, and intelligent paper and cardboard could be the way forward.

Small and Johnson were looking especially to turn "kraft-board", which is produced from New Zealand-grown radiata pine, into something more useful and valuable. Kraft board fibre is exported as newsprint grade paper and that industry is not doing particularly well. X