Watch a wooden knife that is sharper than steel cut through steak

Teng Li at the University of Maryland and his colleagues developed a material called hardened wood which is 23 times harder than raw wood and can be carved to make knives three times sharper than standard steel knives. Nails made from hardened wood were lighter and more sustainable than steel nails, but equally good at holding together three layers of wooden boards that were each 5 millimetres wide.