See-through wood: knotty issue solved

摘要

TRANSPARENT wood just got even better, moving us a step closer to windows that are far better insulators than traditional glass. The standard process for making wood see-through involves soaking it in a vat of sodium chlorite - a chemical compound used in some bleaches - to remove a structural component of the wood called lignin. However, this takes a lot of chemicals, produces liquid waste that is tough to recycle and can weaken the wood. Liangbing Hu at the University of Maryland and his team came up with a method that modifies the lignin instead of removing it completely. It is quicker, uses fewer materials than the usual method and leaves the wood stronger. The researchers' method stems from the recent discovery that lignin can be made transparent by removing only the parts of its molecules that give them their colour. They brushed hydrogen peroxide, which is often used as a disinfectant, over the surface of the wood and then left it under a UV lamp designed to simulate natural sunlight. After soaking the wood in ethanol to remove any remaining gunk, they filled any pores with clear epoxy, a step that is also part of making lignin-free transparent wood.