Cork (material) properties
The cork tree (Quercus suber) has a lifetime of 250 to 350 years and is the only tree whose bark regenerates itself after each extraction. It takes 20 to 25 years before the first cork can be extracted . YOU CAN HARVEST THE BARK ONCE EVERY NINE YEARS.
The roots of the tree go deep into the ground to gain water, and the leaves are a very good sunshade. This is exceptionally important, enabling the trees to cope with very hot summers.Apart from some pruning, cork trees don’t require much maintenance.
But they do require patience, as a Portuguese saying reveals: “if you want to make a business for your grandchildren, plant cork trees.” This is because it usually takes around 25 years before the bark from a cork tree can be harvested for the first time. However, this first harvest, known as virgin cork, is too rigid to use for cork stoppers and instead provides flooring or sound insulation.
It takes the tree nine years to ‘regenerate’ another layer of bark which can be harvested, with this second harvest also used as flooring or sound insulation.The harvest takes place between May-August when it’s easier to peel off the bark, as the level of sap present between the cork bark and the underlying surface of the tree trunk is higher during this period. However, it’s a very delicate, highly skilled and entirely manual operation (attempts to develop an automated process have not been successful).
Harvesters use a particular type of axe to carefully peel off the bark without damaging the tree, otherwise successive harvests will be compromised or even prevented. Only about half of the tree’s bark is peeled off during each harvest, which may cause temporary stress to the tree but also makes the bark grow back more vigorously. Following the harvest, planks of bark are carefully stacked in the open in order to air dry the sap within the bark, which takes six to nine months.
The cork planks are then boiled in water which increases the thickness of the cork, while also removing any foreign objects (eg. dust, insects) embedded in the rugged surface. Natural spring water is used, not tap water, because tap water contains chlorine which reacts with naturally occurring micro-organisms (present for example in the soil) to promote a mold containing TCA (technically 2, 4, 6-Trichloroanisole). This mold emits a pungent, musty odor referred to as ‘corked’.
An adult cork tree produces several hundred pounds at each harvesting and will live for many generations. 50 % of cork production comes from Portugal. The rest comes from Spain, Italy and Northwest Africa.
Now that the wine industry is switching to plastic, the cork industry is focusing on preserving the forests and the communities where cork trees are grown by creating alternative products such as handbags, belts, wallets etc. This is extremely important to provide a way of living for the skilled workers as well as to keep alive the forests that had been in existence for hundreds of years. Cork harvesting is one of the best agricultural jobs in the world, workers can earn around 100 EUR par day .
A southeastern Wisconsin cork company is among more than a dozen manufacturers that are providing parts and products for a NASA venture into space. Cork is a fantastic thermal protector, and will be used in the heat shield on the crew capsule and rocket on the spacecraft that’s expected to take humans to deep space and Mars in coming decades. It’s a heat shield so the astronauts can come home alive.
Cork By Design handbags and wallets selects the finest quality cork bark planks. Colored bags use a water based stain.
Cork is an inherently sustainable resource, both renewable and biodegradable.
- Water resistant, easy to clean with soap and water
- Water repellent
- Mildew and odor resistant
- Mosquito repellent
- Stain resistant
- Fire resistant and flame retardant
- Lightweight material, soft to the touch
- Environmentally renewable, sustainable, natural “green” resource
How to Clean Cork
Cork is one of the most durable and easiest materials to clean. All you need is a cloth or a soft used toothbrush with mild soap or a PH-balanced detergent and water.
A toast to cork! – Videos – CBS News