“Cork is a light, durable, recyclable material with great properties: thermal and acoustic insulation, which makes it suitable for use in any sector”. This remark was made by Ana Tavares, from the panel of experts of the Portuguese Soul programme. According to APCOR, “cork is the bark of the cork oak. It is a 100% natural plant tissue consisting of a hive of microscopic cells containing a gas identical to air and coated primarily with suberin and lignin. It has a range of applications associated with its attributes that no technology has yet managed to emulate, match or exceed”.
It is a 100% natural raw material, that is 100% reusable and 100% recyclable, extracted from cork oaks without harming the normal development of the species and without damaging the tree. The extracted cork is 100% harnessed. Once processed, into stoppers, for example, cork can also re-enter the production process. The cork stoppers can be recycled by shredding. The granules resulting from this process can be used in other products, such as shoes, cladding panels, and fishing buoys.
What does cork give us?
We could say that cork is a super-material, as its intrinsic characteristics do prove it: it is super-light, waterproof, elastic, breathable and recyclable. Its use goes beyond the production of cork stoppers, where Portugal is the market leader.
Lightweight: Over 50% of its volume is air, which makes it very light. It weighs just 0.16 grams per cubic centimetre, and it can float.
Impermeable to liquids and gases: It is totally impermeable to liquids and practically impermeable to gases, thanks to the suberin and cerin present in the composition of cork cells. Its resistance to moisture allows it to grow old without deteriorating.
Elastic and compressible: It can be compressed to around half its thickness without losing any flexibility, and it decompresses, recovering its initial shape and volume as soon as it ceases to be compressed. This flexibility is given by its airtight cells containing a gas mixture similar to air. It is the only solid that when compressed on one side does not increase in volume on the other axis. It is able to adapt to variations in temperature and pressure without suffering variations, due to its elasticity.
Excellent thermal and acoustic insulator: The 40 million cells in each cubic centimetre of cork act as a real decibel absorber, making it an excellent sound and vibration insulator. Its molecular structure allows it to absorb heat and retain it for a long period of time.
Slow burning: The slow combustion of cork makes it a natural fire retardant and a kind of barrier against fires. Cork burns without a flame and does not emit toxic gases during combustion.
Antistatic and anti-allergic: It does not absorb dust and prevents the appearance of mites and, therefore, contributes to protection against allergies.
Wear resistance: Cork is resistant to wear, thanks to its honeycomb structure, which makes it less affected by impact or friction than other hard surfaces.
Cork and footwear
The use of cork for footwear dates back thousands of years: there is historical data indicating that the Romans wore cork sandals, given the level of comfort it provides in contrast with other materials.
Currently, there are several footwear brands that find in this material the perfect symbiosis for the creation of shoes. This is the case of As’portuguesas. Launched by Pedro Abrantes in 2014, the brand revolutionised the market by becoming the first brand of cork flip-flops.
“ASPORTUGUESAS are a new footwear concept that was born with the purpose of creating quality, sustainable & eco-friendly footwear. We are proud to be the world’s first Cork flip-flops brand, using a 100% natural raw material that is born from a tree and retrieved every nine years without the tree ever being cut. We are inspired by Nature, and with our unique choice of Natural & Recycled materials we are committed to giving back!”
Recently launched on the market, New.ve also integrates cork in several models. Coffee bags and grounds, tennis balls, apples, and Tencel are some of the materials that the company already incorporates into its products. “The brand features key materials, such as rubber soles that, being a natural product, can incorporate new, more sustainable ingredients. In this regard, we have a partnership with SBR and incorporate end-of-life tennis balls, coffee grounds, rice husks, cork, and recycled soles, among others”, advances Jorge Fernandes. “In terms of cutting, we can incorporate grape skin, apple skin, cactus bark, hemp and recycled materials such as bottles that are collected from the ocean”.
A second life for cork stoppers
The cork stopper is a natural, recyclable and reusable product. To value and conserve this valuable resource, more and more countries are determined to carry out recycling initiatives to make local populations aware of the richness of this material. Although recycled cork can never be reused to make wine stoppers, there are many alternative applications. For example, display panels, bookmarks, coasters, flooring, coverings, components for the automotive industry, and insulation material, among many others.
In Portugal, there are a number of projects to highlight. In 2008, the Green Cork project was launched by Quercus, in partnership with the Amorim group and Continente supermarkets. Cork stoppers are collected in supermarkets and shopping centres, such as Dolce Vita, and taken to be treated and ground up, transformed into granules, and made into raw material for a second life. The Green Cork idea has spread to various countries such as Spain, the United States, Canada, France, Italy, the United Kingdom, South Africa, and Australia.
It is the planting date of the largest and oldest cork oak tree in the world: the Whistler tree. The name is inspired by the sound of songbirds landing on its branches. It is over 14 metres tall and has a trunk circumference of 4.15 metres.
15 turns around the Earth’s perimeter. This is the number of cork stoppers produced annually around the world.
In 2022, the Portuguese cork industry exported 1200 million euros. The goal is to reach 1.5 billion euros by the end of the decade.
This is the value of the most expensive whisky in the world: the Dalmore Trinitas 64. It is sealed with a Portuguese cork stopper.