" A tree derives its strength from a fibre called cellulose, which is bound together by an organic glue called lignin. Extracting the fibres from the lignin is like trying to remove chewing gum from hair. The process involves crunching up the wood and boiling it up at high temperatures and pressures with a chemical cocktail that depolymerises (breaks down) the lignin and frees up the cellulose fibres. "