Cork is a versatile natural material, used for everything from making bulletin boards to stopping wine bottles. In shoes, the material's usefulness really shines through. Cork outsoles are normally bonded with resin for increased durability. Insoles made from the material offer an anatomically-correct footbed, offering numerous pain-relieving and comfort benefits.
Cork is a relatively soft material that is densely compacted for shoe use. However, when subjected to the weight and heat applied though normal wear, cork insoles mold themselves to the wearer's foot. This creates a custom fit that conforms to the wearer's natural shape, offering a high degree of comfort. Despite its ability to mold to a certain degree, the material stays firm compared to rubber or artificial insoles, maintaining proper arch support and foot alignment.
Cork is a moisture-wicking material. Bacteria feeds on the sweat secreted by feet when inside shoes or sandals. By using cork, there is far less moisture buildup left in the shoe, starving bacteria of food. As a result, any shoe using a cork insole will naturally be relatively odor-free just from normal use.
For those on their feet for extended periods, cork insoles and outsoles offer a degree of relief. The material's natural elasticity means less impact force is transferred up into ankles, shins and knees, reducing joint stress. The material's ability to hold the heel and foot in an orthopedically-correct position -- combined with its shock absorption capacity -- potentially reduces instances of plantar fasciitis and other forms of foot pain. For this reason, many premium shoe manufacturers and medical supply companies offer cork insoles or orthotics to reduce plantar fasciitis pain.
Cork is harvested from cork trees, with the material forming just under the upper bark layer. Cork trees are harvested after 25 years and every nine to 13 years thereafter. The material can only be stripped between May and August to prevent tree damage. The material is recyclable, in turn used for flooring, insulation and new soles.