Series‎ > ‎

How did that cork get in your bottle?

Until Prospero first came to Jimena thirty seven years ago, it had never occurred to him to wonder how that cork ever came to be there, between him and the wine within. In this illustrated series, we try to offer a step-by-step look at the process. The reason, of course, is that Jimena is at the doorstep of one of the best cork oak forests in the world.

(Photos by Alberto & Marcelo Bullrich, José Quirós, Ricardo Gómez and Internet.)



A mature cork oak (Lat. Quercus Suber, alcornoque for single tree, alcornocal for cork oak forest, hence Los Alcornocales) can grow to some 25 m in height. It grows in gentle, Mediterranean climates, and on non-limestone ground, between sea level and up to 1200 m above. It is not resistant to frost. The fruit resembles that of the various oak species, but is less sweet, and much appreciated by pigs (and especially those that become jamón ibérico or serrano).

The bark, which is thick and spongy (under microscope, r.), marks the beginning of this journey. The bark on a cork tree must be left to grow for at least 9 years, when it will be ready for its next harvest. The bark is first ready for removal only when the trunk is 70 cms around at a height of 1.70 metres, which makes the tree about 40 years old. The first three harvests will be no good for bottle stoppers. A tree will live for between 170 and 200 years, which will give only some 15 harvests per tree.

To remove the bark cleanly and as in large a piece as possible, without damaging the tree itself, is a highly skilled, dangerous and well-paid (but seasonal) job but with fewer cutters available each year as the young prefer a less ‘traditional’ trade. It has customarily been done by hand with very sharp axe-type tools specially designed for the purpose. However, a machine has recently been introduced to the area, which ostensibly makes the task easier and no doubt cheaper.

The bark is then collected on the ground and carried, by man or mule, to what is known as a patio, where it is assembled ready to be transported down the mountain to another patio for processing. Loading a mule, too, is also a skilled job, which is why various municipalities in the area hold annual competitions and the skilled labour is running out, as well.

From this patio the harvest must now be transported to the first stage of processing: sorting, classifying, boiling and so on.

The cork is piled awaiting its first sorting by thickness. The thicker, the better, as it fetches more money, but it must meet certain standards of quality as well; for instance, its porosity and thus its ability to 'reject' liquids - we wouldn't want the wine to spill out quietly in the cellar, would we?

The pieces that are not good enough to stamp into corks for bottles gets set aside...

...and bagged. It will eventually be chopped up and minced to be mixed with a setting glue that will allow it to become any number of by-products: cork boards, 'bad' corks for bottles, shoe heels, etc.

Meanwhile, a large vat gets prepared for boiling.

Under the vat is a wood oven with which the water is heated. This process is done in the summer, the work is hard and hot.

The sorted piles of cork are then boiled twice. The first boil gets rid of much of the detritus, and the second ensures that it is expanded to its maximum capability. This procedure can add up to 35% to its thickness, while losing about 15% of the weight. But first it must be allowed to dry properly, which is best done under cover in a draft.

When it is dry, it gets sorted again and cut into smaller blocks...

The bales of cork, sorted by thickness, which requires a lot of experience an plenty of time, is ready for more transportation. Alas, the next part of the process is no longer carried out in Jimena and even the above is in imminent danger. The plants that are left in the village - in Estación, just across from the railway station - are owned by Portuguese companies. The cork is taken to their plants or sold on to others, mostly in Jerez or Valencia for the next step.

(This might be a good place to take a glass or two, so we'll wait for you. Oh, be careful with the cork!)

The cork is now at the cork factory in Portugal, Valencia or Jerez - maybe even in the USA. Before the plank is cut down any further it needs much more accurate calibration if it is of good enough quality. It will be cut into another smaller block and ...

stamped out or even drilled out. It all depends on the quality. Stamping offers a cleaner cork, drilling is faster but fetches less profit.

The next step is a double sterilization process. And then a further, visual selection before final lubrication – it’s difficult enough to get the thing out to get at the wine, so they make it easier for us.

The cork is now ready to go into the bottle but we'll stop the process here and have a drink.

And that’s about it, except for a few loose ends, like what to do with the leftovers, but that’s another story.

However, gleaning the Internet for some of the pictures, we found a couple of things: Do you know why good wine should be ‘laid down’, meaning literally lying down? Because it keeps the cork moist and fully expanded, thus not allowing too much air in - oh, yes, some air gets in: too much and you've got vinegar, too little and the wine won't 'mature in the bottle'.

And do you know how to get a cork out when it’s broken in the neck? No, nor do we, despite years of trying. Cheers!