Cork comes from cork oak bark, which can be harvested every nine to twelve years without harming the tree. Once the bark is collected, it may be cut into cylinders for use in bottling or ground into smaller pieces that are bound together, using a resin derived from natural ingredients, and cut into slabs. The final product is one of the most environmentally friendly materials available. Cork naturally repels fire, mold and mildew, and insects and termites.