First wine cork

Have you ever really thought about the cork in the top of your wine bottle before? To be fair, you’re probably keener to get to the wine inside than ponder the story of the stopper. But that little piece of cylindrical cork is a wondrous thing, a natural phenomenon perfectly suited to its task. It’s lightweight, water resistant, strong, has supreme elasticity, is renewable and recyclable, stops your wine turning to vinegar but also allows just enough air in to help it mature and get more complex. Magic, right?

But how and why did a bit of tree bark start being used for closing wine bottles? And who was the first person to think it was a good idea?  

The story of the wine cork inextricably follows the fortunes of wine, so we’ll need to first head to Greece in around 800 BC. The country had just thrown off the shackles of the so-called ‘Dark Ages’ (a cultural catastrophe) and was starting to trade with the outside world again – and even held the first Olympic Games to celebrate.

The Greeks drank wine, lots of wine, mostly storing it in long terracotta containers called amphorae and shipping it all over the region (some Greek boats could carry up to 3000 of the things!). Naturally, they wanted to protect their beloved wine as much as possible but quickly realised that constant exposure to air turned it to vinegar, especially under the hot Mediterranean sun. So, they went to great lengths to stop the interaction, made more difficult as the clay amphorae were essentially porous. But the ancient Greeks being the ancient Greeks, they came up with an ingenious solution.  

They sealed the inside of every amphora with tree resin, particularly from the terebinth tree (terebinth translates as ‘turpentine’ in English). They supposedly used about 1.5lbs (as confirmed later by an Egyptian potter in 234 AD!), which was enough to put a 1-2mm thick coating over all the exposed clay. But it worked – no air seeped in – and they used the remaining resin to firmly seal a clay stopper to the top. As an extra precaution, the Greeks even added some of the resin to the wine itself to stop bacterial growth and to give it a unique flavouring. The result was retsina, still drunk in Greece today (the etymology of the word retsina is from the ancient Greek word ritini, meaning pine resin). Pliny the Elder, the 1^st century Roman author, would later describe the taste as “an agreeable bouquet together with a certain degree of raciness or piquancy”.

From clay tops in 800 BC, we know the Greeks started experimenting with other more efficient closure techniques. Preserved amphorae from shipwrecks as early as the 4^th or 3^rd centuries, like the Capistello wreck, tell us that Greek tradesmen and sailors were trying everything to keep the air out of their wine – from wood plugs to pinecones to mud. But with amphora necks being as narrow as 12cm, it also made sense that cork stoppers started to be used, albeit seldomly.

In some of the earliest finds, cork was found flush to the rim and sealed with resin or a simple mortar of sand or pozzolana (volcanic ash that sets like concrete) and lime. That’s because these ancient corks weren’t like the tight-fitting ones we’re used to in wine bottles today. They were roughcut bits of cork bark, an inch or two thick, that were forcibly stuffed into the top of an amphora and sealed tight.

Besides the occasional stopper, other common uses for cork in ancient Greece were for fishing floats, the soles of sandals, insulation for soldiers’ helmets and it’s said swimmers sometimes used cork to keep themselves above water! (Later, in Virgil’s Aeneid written between 29 and 19 BC, the baby Camilla – later the famous warrior princess – is saved when her fleeing father puts her in a ‘case’ made of cork and willow and throws her across a river).

Now if we fast forward a bit to Roman times, when Greece became a province of the expanding Roman Empire after its defeat at the Battle of Corinth in 146 BC, keeping wine from oxygenating was still a crucial problem to overcome for such a vino-swilling society.

But cork bungs were gaining in popularity – for amphorae and for wooden casks. In what is probably the first mention of wine corks in literature, the Roman poet Horace, in The Third Book of the Odes (published in 23 BC), Ode VIII, called Celebration, talks of a joyous banquet for Bacchus, the god of wine:

When this festive day returns again I’ll draw

a tight-fitting cork, sealed with pitch, from a jar

laid down to gather the dust in that year when

Tullus was Consul.

This chimes with an obsession by the ruling classes of Rome for aged wines, some of which – like Falernian, a super-prestigious Italian white wine – was matured for ten to twenty years in amphorae with cork stoppers covered with resin or ‘pitch’. (As an aside, the famed ‘Opimian Falernian’ wine vintage from 121 BC was served at a banquet in 60 BC and was still being discussed over 100 years later!)

Now here’s Pliny the Elder again, who was one of the most prolific and important writers on the minutiae of Roman life and loves. His epic work, Natural History (Naturalis historia), was encyclopaedic in scale and scope – weighing in at 37 books, organised into 10 volumes, on subjects as diverse as astronomy to zoology (it’s the largest single work to have survived from the Roman Empire to the modern day). He completed it in 77 AD.

 In Book 14, he talks about a recipe for ‘honey wine’ (which we’d probably now call mead) – including a reference to cork that not only shows it becoming a more popular technique for stoppering amphorae but also to it being used in common language, and as a verb no less.

“A wine is also made of only water and honey. For this it is recommended that rain-water should be stored for five years. Some who are more expert use rain-water as soon as it has fallen, boiling it down to a third of the quantity and adding one part of old honey to three parts of water, and then keeping the mixture in the sun for 40 days after the rising of the Dog-star. Others pour it off after nine days and then cork it up. This beverage is called in Greek ‘water-honey’; with age it attains the flavour of wine. It is nowhere rated more highly than in Phrygia.”

In Book 16, Pliny describes various forest tree species, including the cork tree, which grew in the Mediterranean regions.

“The cork is a very small tree, and its acorns are very bad and few in number; its only useful product is its bark, which is extremely thick and which when cut grows again; when flattened out it has been known to form a sheet as big as 10 feet square. Its use is mainly for ships’ anchor drag-ropes and fishermen’s drag-nets and for the bungs of casks, and also to make soles for women's winter shoes. Consequently, the Greek name for the tree is ‘bark-tree’, which is not inappropriate... It does not grow all over Italy or anywhere in Gaul.”

Around the same time, a Greek physician called Pedanius Dioscorides, who was a surgeon for Nero’s Roman armies, wrote an encyclopaedic book called De materia medica, which went on to become the leading pharmacological textbook for 16 centuries! It was essentially a manual about the medicinal properties of all sorts of plants and minerals, which referenced over 600 species, including cannabis, hemlock, arsenic, as well as defining the curative qualities of more common things like milk and honey. He used corks in many of his experiments – again using the word as a verb multiple times – mostly for keeping his concoctions airtight. Some quotes from various recipes include:

“These are pounded into small pieces and made into little balls the size of half a teaspoonful, dried in the shade, and stored in a jar made without pitch, tightly corked all around.”

This one comes from a description of how to extract bear fat, which he recommends for treating chilblains and promoting the regrowth of hair lost to alopecia:

“Store it in tightly corked ceramic jars and put the jars in a very cold place.”

But after the corking great highs of Greek and Roman wine amphorae came the crashing lows of the Dark Ages in Western Europe from the 5^th century onwards.

Not to simplify the Middle Ages too much, but the fall of the Roman Empire (which collapsed in 476 AD) meant that the harmonious European infrastructure suddenly fell apart as each country or clan did their own thing again. Trade became troublesome and disjointed. Amphorae were replaced with oak casks as they were easier to transport by land, stoppered with more readily available bits of wood. Cork farmers suddenly couldn’t find a market for their product.

The cork industry’s misery was compounded by the rise of The Moors, North African and Arab Muslims, who invaded the Iberian Peninsula in 711 AD, establishing the powerful Islamic kingdom of Al-Andalus. While they brought countless cultural and scientific advancements – especially in maths, medicine and architecture – their religion forbade them from drinking alcohol. So, wine with corks just didn’t feature in their society for nearly 800 years, until well after 1492, when they were expelled by Spain. It meant everything wine-related had to be relearned.

Yet wine in the medieval period was still hugely popular all over Europe. Of course, it had deep religious significance, and winemaking was widely controlled by the Church, but even the poorest serfs drank wine in the Middle Ages, providing much-needed nourishment and immunity – they didn’t know it at the time, but the alcohol content killed bacteria, making it safer to drink than water!

But most wine in this period would have tasted horrible, especially when oxidised. (Interesting fact: most wine sold for higher prices in the autumn when just pressed as it still contained the preservative fizz of carbon dioxide and so tasted ‘normal’). Wine was also often drunk out of wineskins made from tanned animal hides that imparted its own ‘savoury’ flavours. One of the ways medieval winemakers tried to prevent oxidation was to pour a little olive oil into the receptacle – so a film floated on top to stop air contact. Before pouring it, people would dip rags in to soak up the oil, and it’s said the custom of tasting wine before serving was started to make sure there was no oil left!

Cork was clearly desperately needed to save the wine industry… and it was first exported to England in 1307, sent by Denis I of Portugal (the Farmer King), who made cork one of the country’s main exports, alongside wine and oranges. Admittedly, most of the cork was used for footwear in the colder UK, but it was a start.

One of the first English written references to cork being used for stoppering bottles comes from Shakespeare’s As You Like It, a comedic play written in 1599. In act 2, scene 3, his heroine Rosalind – a witty and resourceful lady – says to her cousin Celia, “I pray thee, take the cork out of thy mouth, that I may drink thy tidings”, a clear sign cork closures were becoming more common.

Later, in 1615, Gervase (or Jervis) Markham mentions corks in his snappily titled handbook for housewives, The English Hus-wife, Containing the Inward and Outward Virtues Which Ought to Be in a Complete Woman.

In it, he offers advice on everything from planting herbs and feeding animals to distilling perfume and making pancakes, but also includes detailed instructions on bottling beer:

“You should put it into round bottles with narrow mouths, and then, stopping them close with corks, set them in a cold cellar up to the waist in sand, and be sure that the corks be fast tied in with strong pack thread, for fear of rising out and taking vent, which is the utter spoil of the ale.”

The real breakthrough came with the rise of sturdier and cheaper glass bottles. Most ‘bottles’ at the time were made of pottery or stoneware – and in the ale houses, wine or beer was simply ladled from a barrel and served in mugs or decanters. That started changing when Sir Kenelm Digby, a somewhat eccentric courtier, diplomat, privateer, scientist, author and all-round intellect, started manufacturing ‘glass onions’ (small, rounded bottles) from his glassworks in Newnham-on-Severn in around the 1630s.

His improved manufacturing techniques (using coal and a wind tunnel to make his furnace hotter) made bottles stronger and more stable. They were also green or brown so protected the liquid inside from light. Being stronger also meant they didn’t break when a cork was pushed deep into the neck, tied to a bit of twine. But as the corkscrew hadn’t been invented yet, they were left simply sticking out.

With these new bottles came the opportunity for branding and status. The privileged classes would now buy wine by the barrel but quickly decant it into corked bottles complete with the family seal. Their favoured servants were charged with the task – they were the ‘bottler’ (from the French ‘bouteillier’), a word which gradually evolved into ‘butler’.

So, by now winemakers and drinkers knew corks were essential for preserving the quality of their favourite tipple but they didn’t know why. Enter Robert Hooke, an English polymath, and one of the first scientists to investigate living things at a microscopic level. In 1665, using a compound microscope he designed himself, he looked at a slice of cork, coining the term ‘cell’ for the first time in his seminal book Micrographia as he described the hexagonal structure.

“I could exceedingly plainly perceive it to be all perforated and porous, much like a Honey-comb… Next, in that these pores, or cells, were not very deep, but consisted of a great many little Boxes […] these […] were indeed the first microscopical pores I ever saw, and perhaps, that were ever seen, for I had not met with any Writer or Person, that had made any mention of them before this.”

What he was discovering and confirming was that cork was the PERFECT material for sealing bottles. The bark is made of water-resistant cells that when compressed, form a cushion that adapts to the bottle's neck, creating a durable seal that protects the wine whilst also allowing it to breath. The best corks (today) allow just 1 milligram of oxygen to enter a bottle each year – enough to remove any sulphites added in the bottling process but also help the wine naturally mature and become more complex.

By the 1730s, the cork had pretty much become the standard bottle closure all over Europe. Later in France, a writer called Denis Diderot was putting the finishing touches to his magnus opus – the first ever French encyclopaedia called The Encyclopaedia or Reasoned Dictionary of Sciences, Arts and Crafts.

Published in 1751, it was the synthesis of all modern knowledge of the time and included an entry for cork alongside an illustration of ‘the manufacture of cork stoppers’. Some of the accompanying text says that cork was used for shoes and slippers “but above all to close jugs and bottles”.

All this evidence hopefully lays out enough proof to debunk the popular urban myth that Dom Pérignon, the French Benedictine monk and sparkling wine enthusiast, was the first to use corks on a grand scale for his champagne.

Of course, bottle shapes naturally evolved and changed over the years, becoming squatter or thinner depending on the liquid inside and the glassmaker. But by the 1820s or so, wine bottles were becoming more standardised, especially when Ricketts & Co Glassworks of Bristol (England) patented a machine that could manufacture bottles of identical size and shape using a three-piece iron mould. The long thin necks all required a cork stopper of course.

After all the wars, alliances, invasions, political upheavals, blockades and other European shenanigans, the cork trade was now booming again. At first, Spain emerged as the world’s leading cork producer (some experts still believe the best corks come from Catalonia, Spain, citing a higher density) but it eventually lost its status to Portugal. Not only do cork trees grow more prolifically, The Spanish Civil War in the 1930s cut Spain off from most of its markets, helping Portugal take its crown.

Today, cork production is a serious business. Under Portuguese law, a cork tree cannot be harvested until it grows to 70cm in diameter and 1.2m in height, which usually takes about 25 years. The first harvest is generally poor and used for shoes. After another ten years or so, it can be harvested again. But only on the third harvest, when the tree is nearly 50 years old, is the cork sufficiently dense to be used for stoppers. It’s not a business for the faint-hearted – or people looking for a quick buck! The trees usually have a lifespan of about 150-200 years but the oldest one known is Whistler Tree, which was planted in 1783 in Águas de Moura, Southern Portugal, is over 14m tall and has produced over 100,000 cork stoppers since!  

No one should underestimate the humble wine cork again. It comes with a complex and culturally rich story that spans over 2500 years and countless pioneering polymaths. Through its beautiful form and flawless function, it has won hearts and earned its rightful place at the top of the wine bottle. And while it may have survived everything from Caesars to booze cruisers, it seems the only thing it needs to worry about now is the screwcap…