How cork is made: an illustrated guideHow cork is made An illustrated guide to the cork production process It all starts in the forest. Cork oaks are harvested every nine years, once they reach maturity. It doesn't harm the tree, and the cork bark regrows. Most cork forests are in Portugal and Spain. The year of harvest is marked on the trunk, so each tree isn't harvested at the wrong time. Cork is a great insulating material, and giv
