Material in Focus: Cork
Cork is one of the most versatile natural materials.
A natural material, cork is layers of bark tissue that is harvested primarily from the cork oak, which is endemic to southwest Europe and northwest Africa. The Montado landscape of Portugal produces approximately half of cork harvested annually worldwide (200,000 tons), with Corticeira Amorim being the leading company in the industry for commercial use.
Once the cork oak trees are about 25 years old the cork is stripped from the trunks every nine years. Cork production is generally considered sustainable because the cork tree is not cut down to obtain cork; only the bark is stripped to harvest the cork. The tree continues to live and grow for about 300 years. The sustainability of production and the easy recycling of cork products and by-products are two of its most distinctive aspects.
Cork hold some amazing properties and is lightweight, holds low density, is near-impermeable, buoyant, elastic, hold fire retardant properties and is moisture resistant.
It is used in a variety of products, the most common of which is wine stoppers, which represent about 60% of all cork based production. The by-product of the stopper production, corkboard, is gaining popularity as a non-allergenic, easy-to-handle and safe alternative to petrochemical-based insulation products. Its also used to make bulletin boards as well as floor and wall tiles.
Other interesting uses of cork: (do you know any more?)
- In architecture, cork is often used as a lining material, flooring, façade panels, expanded panels and for decorative use. It has been used instead of wood or aluminium in automotive interiors and as a core material in sandwich composite construction. It is also often used as acoustic and thermal insulation in house walls, floors, ceilings and facades and in sprayable form as cork plaster.
- Granules of cork can also be mixed into concrete. The composites made by mixing cork granules and cement have lower thermal conductivity, lower density and good energy absorption.
- As industrial application, cork is an excellent gasket material. It is often used, in various forms, in spacecraft heat shields and fairings and in the paper pick-up mechanisms in inkjet and laser printers.
- In the design world, cork fabric can form an alternative to leather in handbags, wallets and other fashion items. It can be used to make watch bands and faces as well as badminton shuttlecocks and the core of both baseballs and cricket balls. Cork is used in musical instruments, particularly woodwind instruments, where it is used to fasten together segments of the instrument, making the seams airtight.
- In the marine environment it is used as fishing floats and buoys.
What an amazing material, and its natural!