At Icon Footwear, many of the brands we carry in store use cork in their footbeds, so I thought it was time to walk you through the pros and cons of cork—and just how it can have a positive impact on sustainability.
Because sustainability, particularly from sustainable shoe brands, is such an important topic, I’ll start there. But what does sustainability actually mean in the footwear world? In our industry, it really comes down to three key areas:
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Materials – What the shoe is made from, how those materials are sourced, and whether they can be considered self-sustaining.
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Engineering – How the shoe is constructed, the manufacturing process, and how easily it can be reused, resoled, or recycled.
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Social responsibility – How the workers involved in sourcing materials and making the shoes are treated, including fair wages and safe working conditions.
The growing and harvesting of cork for sustainable footwear
A cork tree is a type of oak (Quercus suber) with a lifespan of around 150–200 years. The wonderful thing about these trees is that cork is simply the outer bark, which means it can be harvested without cutting the tree down. Harvesting takes place between May and August, during Europe’s summer months, when cork oak forests are at their most active. Skilled workers make precise horizontal and vertical cuts in the bark and then carefully peel away sections. The craft lies in removing only the outermost layer—the thick, spongy protective layer called the phellem—while leaving the inner layers intact.
Beneath this sits the phellogen (or cork cambium), a regenerative layer that continuously produces new cork cells. This ethical production method is the engine of renewal: after each harvest, the phellogen rebuilds the phellem, allowing the tree to be harvested again roughly every 9 to 12 years. The innermost bark, which carries nutrients throughout the tree, remains completely undisturbed.
Environmentally, cork oaks are exceptional carbon storers. As the tree repairs and replaces its outer bark, its uptake of CO₂ increases significantly—often outpacing many other types of vegetation. Well-managed cork oak forests in Portugal can sequester up to 14.7 tonnes of CO₂ per hectare each year, making them important allies in the fight against climate change with their innovative materials.
Cork footbeds and your knees, hips, and back
Cork footbeds are excellent for joint comfort because cork is inherently spongy. and promotes sustainable practices. Its structure contains around 40 million airtight cells in just one cubic centimetre, creating a honeycomb-like material that compresses under pressure (up to about half its thickness) and then springs back to shape. The cells don’t bow outward; instead, the air inside compresses and expands as pressure is applied and released.
Cork footbeds also gradually mold to your unique foot shape. As you walk, the footbed adapts to reduce pressure points and provide customised support for your foot arch, toes, and heel. This happens because the cork cells subtly rearrange under repeated pressure, settling into a pattern that supports your foot while still maintaining that signature springiness with sustainable materials.
Other beneficial factors
Beyond joint comfort, cork offers great thermal insulation—keeping your feet warm regardless of ground temperature. It's also naturally antimicrobial, resisting mould and bacteria that cause foot odour. And unlike many materials, cork doesn't become soggy when your feet sweat; it manages moisture beautifully while staying resilient.
Why does a cork footbed darken over time?
That darkening you notice is due to a natural chemical reaction. While cork doesn't get soggy from sweat, its cellular structure does allow foot oils, sebum, and dead skin cells to work their way between some of the cork cells. Once embedded, these oils oxidise when exposed to air—causing the characteristic darkening. This happens with other natural footbed materials too, like the leather coverings on good shoes such as Birkenstock or Naot footbeds.
If your footbed is made of raw, uncovered cork, another factor can contribute: tannins naturally present in cork can react with trace metals and salts in sweat, deepening the color further. This buildup is sometimes called a "grime layer"—and while cork itself resists mold and bacteria, the oils and dead skin your foot leaves behind can still harbor unwanted microbes. Fortunately, cork's natural resistance keeps the overall impact minimal. To reduce buildup, try making a paste with baking soda, applying it to the footbed, letting it sit briefly, then wiping it away with a damp cloth. Avoid getting the cork overly wet, and never submerge the shoe for a deep scrub—gentle care preserves the material best.
Durability of cork footbeds
Most quality cork footbeds (like those in Birkenstock and similar brands) blend granulated cork with natural latex derived from the sap of the Para rubber tree. The latex binds the cork particles together and acts as a protective coating for enhanced longevity. When you first buy cork-soled shoes, you'll often see the latex visibly coating the footbed edges. Over time and with wear, this latex layer gradually breaks down, exposing the cork beneath and potentially leading to crumbling. A simple way to extend your footbed's life? Apply a cork sealer to the edges as the latex wears away.
Conclusion
Cork is truly an amazing material—giving you a literal spring in your step through its responsive, spongy nature. Every step delivers not just comfort but genuine joint protection. And what's even more fantastic? Cork is completely sustainable and carbon neutral: harvested without harming the tree, actively reducing CO₂ emissions, and at end-of-life, fully biodegradable or recyclable. It's comfort you can feel good about—literally and environmentally.
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