What are cork's natural properties?

The tree and the harvest

• Cork is the bark of the cork oak, stripped by hand from the living tree. The tree is never cut down to harvest it.
• A cork oak is first stripped at about 25 years old, and Portuguese law forbids stripping the same tree more often than every nine years.
• A cork oak lives 150 to 200 years and is stripped about 15 times in its life, regrowing its bark each time.
• In Portugal the cork oak is the national tree, and it may only be felled if dead or diseased, with written permission.
• The bark grows back after every harvest, and a regularly stripped tree yields far more cork over its life than one left alone.

Carbon and the forest

• Cork oak woodland takes up carbon every year; studies in Portugal measured roughly 1 to 15 tonnes of CO2 per hectare, depending on tree density and rainfall.
• Carbon the cork oak drew from the air stays stored in the cork for as long as the product is in use.
• Cork oak woodland is home to more than 160 bird species and 37 mammal species, including the rare Iberian lynx and Spanish imperial eagle.
• Cork oak woodland protects soil from erosion, helps rainwater soak into the ground and acts as a barrier against desertification.

What the material does

• One cubic centimetre of cork holds about 40 million sealed cells. Robert Hooke first described and named the 'cell' by looking at cork in 1665.
• Natural cork weighs only about 120 to 240 kg per cubic metre, and decorative agglomerated cork about 200 to 350, a third or less of the weight of water.
• Natural cork floats, because its cells are closed and filled with gas, which is why it has been used for floats since ancient times.
• Cork can be squeezed to about half its thickness without its cells breaking, and it springs back almost fully when the pressure is released.
• Squeezed from one side, cork barely bulges out at the other sides, which helps a stopper fit tightly in a bottle neck.
• Suberin, a waxy substance lining every cork cell, makes cork highly resistant to liquids, which is why it has sealed wine for centuries.
• Natural cork lets only a very small amount of air through, slowly enough for wine to keep ageing under a cork stopper.
• Cork is a poor conductor of heat, about 0.045 W/m·K, so it slows heat passing from a hot pot or mug into the table.
• Cork is soft to the hand and feels warm, because it draws very little heat away from your skin.
• Cork has a naturally high coefficient of friction, which is why it is used for shoe soles, tool handles and floors.
• Cork absorbs the energy of knocks and impacts, which is why it is used in shoe soles, flooring and protective packaging.
• Cork's honeycomb of cells makes it resistant to wear from everyday rubbing and handling.
• Cork resists moisture, and so resists rot and decay, letting it age without deteriorating.
• Suberin, cork's main component, does not dissolve in water or alcohol, one reason natural cork is trusted to seal wine and spirits.
• Published research found natural antibacterial activity in cork, strongest against Staphylococcus aureus.

At the end of its life

• Cork is recyclable. Used wine corks are collected in many countries and ground into granules for new products, including coasters and place mats.
• Natural cork is biodegradable, though slowly, because its suberin resists decay until fungi break it down.
• In agglomerated cork the granules are held by a resin binder, so it is the cork, not the finished piece, that is biodegradable.

Five thousand years of use

People have used cork for more than 5,000 years, from sealing containers in ancient Egypt and Persia to today's wine stoppers.

What these facts apply to

These are properties of cork the material, from the sources listed below. Most of what we make is agglomerated cork, granules bound together, so the natural-cork facts about floating, air and chemical stability describe the raw material rather than a finished coaster or mat.

Our wall panels are a 3 to 4 mm decorative finish, and none of the heat, impact or sound properties above is claimed for them.

Is cork renewable?

Yes. Cork is the bark of the cork oak, stripped by hand from the living tree, which regrows it. A tree is first stripped at about 25 years old, then no more often than every nine years, and lives 150 to 200 years.

Does cork store carbon?

Cork oak woodland takes up carbon every year, roughly 1 to 15 tonnes of CO2 per hectare in Portuguese studies depending on tree density and rainfall, and the carbon in the cork stays stored while the product is in use.

Is cork biodegradable?

Natural cork is, slowly, because its suberin resists decay until fungi break it down. In agglomerated cork, granules held by a resin binder, it is the cork rather than the finished piece that is biodegradable.