How Are Wine Corks Made?

As a wine drinker or collector, you may know a lot about the drink itself, but how much do you know about the small piece of cork that keeps the precious drink from spilling or spoiling? The process of producing a wine cork is lengthy, yet interesting. We take a look at how it is done. 

The Tree

Cork is formed from the bark of a Cork Oak Tree. These trees are predominantly found in Mediterranean countries such as Spain and Portugal.  The tree reaches maturity after around 25 years of growing. Once maturity has been reached, specially trained cork harvesters will begin to strip the bark using an axe. The whole process of removing the bark is done skilfully by hand. The year the cork is harvested from a particular tree will be marked on the tree so that it isn’t harvested again too soon. The tree needs a minimum of nine years to regrow enough bark to be harvestable again. Typically, trees will be harvested every nine to twelve years. This process does not harm the tree, making it a sustainable and renewable resource for the wine industry. With a lifespan of between 150 and 250 years, each tree is able to provide around 12 harvests worth of cork throughout its lifetime. 

Of the 340,000 tonnes of cork that is gathered each year, only 15% of that gets made into wine corks; however, the wine industry brings over 66% of the cork industry’s revenue from that amount!


Preparing the Bark

Before anything happens with the bark, it will be left outside for a few months to cure. The planks of cork will be loaded up on palettes and taken to a processing facility to be cleaned. Firstly they will be boiled, which helps to both clean the cork and soften it up. Boiled planks are also usually flatter, making them easier to work with and turn into corks. The water it is soaked in will also contain a fungicide to ensure that the cork is free of any bad fungus or mould. At this time, any bad, or low-quality bark will be stripped away. The remaining planks will be stacked up and left in a humidity-controlled space for a few weeks. 


Cutting the Corks

Each plank is then graded based on quality and cut into smaller strips. The best cork is sent to be hand punched into corks, while the rest will be ground up to make technical corks. They may then be further cleaned and sterilised. Next, the corks are sorted both optically by a machine and then again by eye to ensure that the corks are organised by the correct grading. The top grade cork will be the most expensive, and will be used to make the best wine bottles complete! 

Technical Corks

Many pieces of bark will be too thin to form a high-quality natural cork out of, as it needs to be thick enough to have no gaps at all to stop wine spilling out! There is also leftover cork between the strips where corks are punched out that can be used. To stop bark going to waste, the remaining pieces of cork are ground up and then fused together to form a ‘technical cork’. This allows less wastage of cork, and produces some great closures for cheaper bottles!


After the Wine

Each year around 13 billion wine corks are produced. Many of these remain in wine drinkers collections or end up in a landfill. But did you know that these corks can be recycled into other products? While they cannot be reused as a wine cork, they can be turned into corkboards or cork flooring, giving new life to the cork.


Do you have a collection of wine corks? If so, where do you keep it; in the kitchen, your wine cellar, or somewhere else? Let us know in the comments below!


1 comment

  • Kat

    Very interesting. Don’t think I really knew much about cork. And yes I have a cork collection!

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