As many of us might know, cork is widely used as wine bottle stopper, but if you have not been exposed to cork products before, you may wonder what kind of material is cork and what are its benefits? Let’s take a closer look at.
What is cork?
Cork is the outer layer of the Cork Oak tree(also called Quercus Suber), this tree is unique and evergreen in nature, which are found in forests surrounding the West Mediterranean Sea, they are cultivated in Spain, Italy, France, Morocco, Tunisia, Algeria and China. Particularly, Portugal is the world’s largest cork producer,
Cork can be removed periodically, usually every 9-12 years, from the tree without harming it. However, the cork oak must be about 20-25 years old before removing bark for the first time. The entire process does not involve cutting down any trees, it most definitely is a 100% natural, organic and eco-friendly material.
Cork is a unique natural plant tissue, a beehive of microscopic cells surrounded by a gas (identical to the air we breathe) and covered mostly by suberin and lignin. Suberin is a natural, highly hydrophobic wax, while lignin (which is a polymer found in various terrestrial plants) is responsible for imparting rigidity, impermeability and resistance to it.
Cork is closely related to the maintenance of biodiversity, the heart of sustainable development, and the reduction of emissions and sequestration of CO2, aspects that, additionally to the environmental importance, are also economically very important。
Significant reductions in emissions of greenhouse gases in the construction sector can be achieved through various measures for energy savings, an area where cork derivatives can have a very important role, particularly regarding the thermal performance of buildings, but not only. Cork used in floor coverings, wall coverings, and other decorative applications also contribute to this. Also considered are green building and sustainable materials which are concepts that are increasingly considered by engineers, architects and other technicians and even by consumers.
What does cork contain?
Cork composition varies depending on geographic origin, climate and soil conditions, genetic origin, tree dimensions, age (virgin or reproduction), and growth conditions. However, in general, cork is composed by:
- suberin (45%)
- lignin (27%)
- polysaccharides (12%)
- ceroids (6%)
- tannins (6%)
Suberin, being the main component of cork, is a mixture of organic acids that coat the walls of the cork cells, preventing the passage of water and of gases. The properties of suberin are notable: it is practically infusible and is insoluble in water, alcohol, ether, chloroform, concentrated sulphuric acid, etc.
Cork presents a characteristic cellular structure in which the cells have usually a pentagonal or hexagonal shape. The cellular wall consists of a thin, lignin rich middle lamella (internal primary wall), a thick secondary wall made up from alternating suberin and wax lamella and a thin tertiary wall of polysaccharides. Some studies suggest that the secondary wall is lignified, and therefore, may not consist exclusively of suberin and waxes. The cells of cork are filled with a gas mixture similar to the air, making them behave as authentic “pads”, which contributes to the capability of cork recover after compressed.
The history of cork:
Cork History goes back in time to 3000 BC cork being used in fishing tackle in China, Egypt, Babylon and Persia. In Italy remains dating from the 4th century BC, having been found artefacts such as floats, stoppers for casks, women’s footwear and roofing materials. Also dating from that period is one of the first references to the cork oak, by the Greek philosopher Theophrastus who, in his botanical treatises, referred in wonder to “the ability that this tree has to renew its bark after it has been removed”.
As the years went on, cork continued to find its main use as a bottle stopper, and at a time when wine or beer was safer to drink than most water, this was vital. Up until the mid 1700’s, it was usually harvested from where it was growing naturally, but its increasing use led to it being purposefully cultivated. Starting in 1688, Pierre Perignon used corks held in place with wire to seal bottles of his latest creation, champagne.
In 1892, the mass produced cork lined crown cap lid ( better known as a bottle cap) was invented by American William Painter, who became very wealthy from his invention. It was the industry standard until 1955, when it was replaced by the plastic stopper.
A German company developed a method in 1890 for using waste cork. They combined it with a binding agent so that it could be rolled into sheets to be cut into whatever shape was desired. This is called agglomerated or compound cork. John Smith discovered that, by using heat and pressure to release the naturally occurring resins, he could create a conglomerate of cork particles that didn’t need any binder. Charles McManus found a method of producing agglomerated cork that could be used to line bottle caps, and since then, others have carried on in his footsteps and found new and innovative ways of reusing waste cork and the byproducts of its production.
Finally, all the signs are that in the 21st century, environmental concerns have become a constant, the use of an ecological, recyclable and biodegradable material such as cork has increased, particularly in innovative areas such as Design for Sustainability and Eco-Design. Increasingly, new generations of artists seek to create everyday objects – articles for the table, kitchen, leisure, furniture – from the “fruits of the earth”, materials that are one hundred per cent natural and contribute to environmental sustainability.
What is a cork made out of? Is it wood?
Kind of. Cork is made from the bark of a tree, Quercus suber, or the cork oak. These trees can grow pretty big, and they have really thick, rugged bark. One plus side to cork cultivation is that you don’t have to chop down a tree to make corks—you can harvest the bark without harming the tree, and then do it again in about another 10 years.
Cork is a pretty remarkable material—it’s elastic, strong and relatively impermeable to air. But there are some downsides to cork, too, including its susceptibility to the chemical compound TCA, or 2,4,6-trichloroanisole, and its musty, “corky” notes.
It takes each cork oak 25 years before it can be stripped for the first time and it is only from the third stripping (at 43 years of age) that the cork, has the high standard of quality required for producing cork stoppers. The first two harvests – the «virgin» cork and «secundeira» cork –, as well as that removed from the base of the tree,
The cork tree thoroughly develops the bark over the years. And man develops a refined technique for harvesting it. The cork is harvested by specialized professionals, always between May and August, when the tree is at its most active phase of growth and it is easier to strip without damaging the trunk. The cork oak is the only tree whose bark regenerates, acquiring a smoother texture following each harvest. Over the course of its lifetime, which on average lasts 200 years, it may be stripped around 17 times.
Is cork Eco friendly?
Cork is a natural, environmentally friendly material. It biodegrades completely and can be easily recycled without producing any toxic residues.
More companies than ever are choose to make their products eco-friendly. Over the past few years, products such as cork shoes, flooring, and yoga mats have started to pop up frequently.
Is cork vegan?
High quality vegan accessories are a good example of cork’s versatility.
Although cork is not wood, it is a dead tissue, which makes it an inert substance. Meaning no taste and, more importantly, no odors will be released by it. This has great hygienic value, another characteristic highly appreciated by the transformative and creative industries. Another distinctive quality is its durability, or, better said, its capacity for retaining its original conditions. This makes it a perfect candidate for durable, high quality vegan accessories.
Is cork reusable and recyclable?
Cork is 100% natural, reusable and recyclable materials. We have already established that cork is the outer bark of the cork oak tree (Quercus suber L.), whether from the environmental, social or economic perspectives, cork is one of the world’s most versatile materials.
Is cork a sustainable material?
Yes, cork is a sustainable material because the cork tree is not cut down to obtain cork. It is only the bark that is stripped to harvest the cork. The tree continues to live and grow. In fact, cork’s sustainability and easy recycling of its products are two of its most distinctive features.