How did that cork get in your bottle?


Until I first came to my little village in the mountains forty three years ago, it had never occurred to me to wonder how that cork ever came to be there, between me and my wine within. So, curiosity being one of my vices, I hereby offer you a step-by-step look at the process. (Some of you will have read it on another, abandoned blog, so apologies) The reason, of course, is that the village is at the doorstep of one of the best cork oak forests in the world, and the largest in Europe. (Photos by Alberto & Marcelo Bullrich, José Quirós, Ricardo Gómez and Internet.)

C01It all starts here
A mature cork oak (Lat. Quercus Suber. In Spanish alcornoque for single tree, alcornocal for cork oak forest, hence Los Alcornocales Nature Park) 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).

 C02BC02AThe 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 nine 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.

C03ATo remove the bark cleanly and as in large a piece as possible, without damaging the tree trunk itself, is a highly skilled, dangerous and well-paid (but seasonal) job and with fewer cutters available each year as the young prefer a less ‘traditional’ trade. It has customarily been done by hand with very sharp ax-type tools specially designed for the purpose. In the field you will see the cutters sharpening their tools constantly, The sound rings around the valley all the time.

However, a machine has recently been introduced to the area, which ostensibly makesC03B the task easier and no doubt cheaper. It is probably the only way to handle the present labour situation, but bodes badly for changing economies in the area, which have for centuries depended on Los Alcornocales Nature Park to put food on the table.

C04AC04BC04CThe 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 this skilled labour is running out, as well.

C05From this patio the harvest must now be transported to the first stage of processing: sorting, classifying, boiling and so on, as you will see. Loading the trucks is also a skilled job, though anyone who’s driven behind one of them in the late summer might be alarmed and not believe it.

C06The 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 are mightily important – we wouldn’t want the wine to spill out quietly in the cellar, would we?

C07The pieces that are not good enough to stamp into corks for bottles get set aside…

C08…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. As you will also see below.


(The photos detailing this part of the process were taken in the last remaining such facilities in the village, which have since closed.)

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.

C10AThe 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.

C11AWhen it is dry, it gets sorted again and cut into smaller blocks…

C11BThe bales, sorted by thickness, which requires a lot of experience and plenty of time, is ready for more transportation.

C12ACork merchants, the middlemen, used to come to the village to buy the processed cork and take their acquisitions to Portugal for finalising and turning into bottle stoppers. Middlemen also came from Jerez, Valencia and other places within Spain. A finishing factory was never established in the village. Eventually the three processing facilities (one of which is used here as illustration) were sold to Portuguese companies. There is nothing left now.

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

C13AC13BThe 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 …

C14…stamped or drilled out. It all depends on the quality: Stamping offers a cleaner cork, drilling is faster but fetches less profit.

C15aThe 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.

C16The 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.

A bit more: gleaning the Internet for some of the pictures, we found a couple of things:

C18Do 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’.

C19And do you know how to get a cork out when it’s broken in the neck? No, nor do I, despite years of trying. I gave up the booze in revenge!


(C) Copyright Alberto Bullrich 2015

One thought on “How did that cork get in your bottle?

  1. Such an interesting article. What a shame that the youngsters coming up today are not interested in keeping their heritage going.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s