When one picks up a piece of cork, they usually take it for granted, not knowing anything about its chemical makeup or origin. All they know is that it’s an excellent sealant and floats on water.

Little do they know that cork is harvested from living cork oak trees, where the outer bark, or cork, is stripped off the bark, leaving the tree alive and still growing. It’s very similar to how wool is taken off a sheep.

What Exactly Is Cork?

One of the first things to know is how cork is formed. Cork is essentially made up of nothing but dead cells that accumulate on the surface of the cork oak tree. When one takes a closer look at cork, such as under a microscope or even magnifying glass, they’ll find a honeycomb-like structure, making the cork extremely porous. In fact, cork has only one fourth the density of water.

Aside from making water-tight seals, the extremely porous nature of cork makes it an excellent thermal and noise insulator. Not only that, but the porous nature of cork makes it extremely fire resistant, only charring the surface when exposed to fire. On top of that, cork resists dust, moisture, rot and insects.

More About the Cork Tree

A cork tree, on average, reaches to about 40 to 60 feet in height, with a trunk circumference of six to 10 feet. A cork tree has to reach at least 20 years old before it can even be harvested. On top of that, the first batch is usually of pretty low quality, being used for agglomerated cork products. After that, subsequent harvests occur at nine-year intervals.

Each tree has a lifespan of about 150 years. A smaller, younger cork tree will yield about 35 pounds of cork, whereas an older tree will yield 500 pounds easy. Due to the large time intervals between harvests, many trees must be grown to keep up with the world’s demand. Around half of the world’s cork supply comes from Portugal.

Even to this day, there’s still a very high demand for cork, thanks to its amazing natural abilities to seal against water, moisture, noise, heat, fungus and other elements for an exceptionally long time. Although the tree takes many years before it can be harvested again, the yield that it produces in those intervals is more than sufficient, especially when grown in large numbers.

Also see:

Where Does Cork Come From?
What Are Cork Cells?
Is Cork a Type of Wood?
How to Make Cork?
What Tree Does Cork come From?
Are Cork Trees Endangered?
What Country is the Leading Producer of Cork?
How is Cork Harvested?