Chemicals, Casks, Crowns & Corks

by Sally Steele

Cork Trees in Portugal, photograph by Kim Steele

Depending on your perspective, as a Boulevardier, one of these might come to mind as a place to start perusing this post…

What contemptible scoundrel has stolen the cork to my lunch?      ~W. Clement Stone

His heart danced upon her movement like a cork upon a tide.        ~James Joyce

What you learn after you are 40 is that it is just about plugging up holes in the boat. You just hope you have enough corks to plug enough of the holes.             ~George Clooney

I, of course, have a totally different cork profile–my spouse, Boulevardiers Publisher, Kim Steele, has many square feet of glorious cork in his studio. My appreciation for cork has always been abundant, I now further associate it with being able to share productive times, in Kim’s studio, looking at oh-so-beautiful images. (note: all images in this cork post are by photographer & Boulevardiers Publisher, Kim Steele, from a recent visit to the country where he spent 4 years of his childhood with his family, his father as U.S. Military Attaché)

Cork Trees in Portugal, photograph by Kim Steele

Back to business, and history.

Cork Harvesting in Portugal, photograph by Kim Steele

Cool Cork Facts & History from Wikipedia:

~Cork is used in musical instruments, particularly woodwind instruments, where it is used to fasten together segments of the instrument, making the seams airtight. Low quality conducting baton handles are also often made out of cork.

~Cork can be used to make bricks for the outer walls of houses, as in Portugal’s pavilion at Expo 2000.

~Cork’s bubble-form structure and natural fire retardant make it suitable for acoustic and thermal insulation in house walls, floors, ceilings and facades.

~The Cork Oak is unrelated to the “cork trees” (Phellodendron), which have corky bark but are not used for cork production.

~On November 28, 2007, the Portuguese national postal service CTT issued the world’s first postage stamp made of cork.

Cork Tree Harvesting, Portugal, photograph by Kim Steele





Cork is the outer bark of an evergreen oak known by the Latin name Quercus (oak) Suber (cork). Today, the center of the world’s cork oak forest is concentrated in Southern Europe; Portugal, Spain, Italy & France, which accounts for 67% of the cork oak production. North Africa has the remaining 33%. The total land surface occupied by this oak is 2.2 million hectares (5.434 million acres), of which Portugal and Spain represent 56%.


The sale of cork and cork products by producers, to the European and United States market, exceeds $1.5 billion annually. Of this value, the cork stopper is $1.1 billion, while the sale of agglomerated cork, cork flooring, and other related products is $400 million.

Cork Tree Grove, Portugal, photograph by Kim Steele

Wikipedia: The rare cork tree can live for 2,000 years. The cork industry is generally regarded as environmentally friendly. Cork production is considered sustainable because the cork tree is not cut down to obtain cork; only the bark is stripped to harvest the cork. The tree continues to live and grow. The sustainability of production and the easy recycling of cork products and by-products are two of its most distinctive aspects. Cork Oak forests also prevent desertification, are a particular habitat in the Iberian Peninsula, and the refuge of various endangered species.

Cork is extracted only from early May to late August, when the cork can be separated from the tree without causing permanent damage. When the tree reaches 25–30 years of age and about 24 in (60 cm) in circumference, cork can be removed for the first time. However, this first harvest almost always produces poor quality or “virgin” cork (Portuguese cortiça virgem; Spanish corcho bornizo or corcho virgen). Bark from initial harvests can be used to make flooring, shoes, insulation and other industrial products. Subsequent extractions usually occur at intervals of 9 years, though it can take up to 13 for the cork to reach an acceptable size. If the product is of high quality it is known as “gentle” cork (Portuguese cortiça amadia, but also cortiça secundeira only if it is the second time; Spanish corcho segundero, also restricted to the “second time”), and, ideally, is used to make stoppers for wine and champagne bottles.

The workers who specialize in removing the cork are known as extractors. An extractor uses a very sharp axe to make two types of cuts on the tree: one horizontal cut around the plant, called a crown or necklace, at a height of about 2-3 times the circumference of the tree, and several vertical cuts called rulers or openings. This is the most delicate phase of the work because, even though cutting the cork requires significant force, the extractor must not damage the underlying phellogen or the tree will be harmed. To free the cork from the tree, the extractor pushes the handle of the axe into the rulers. A good extractor needs to use a firm but precise touch in order to free a large amount of cork without damaging the product or tree. These freed portions of the cork are called planks. The planks are usually carried off by hand since cork forests are rarely accessible to vehicles. The cork is stacked in piles in the forest or in yards at a factory, and traditionally, left to dry, after which it can be loaded onto a truck and shipped to a processor.

Old Cork Tree, Portugal, photograph by Kim Steele

Cork stoppers were found in tombs from ancient Egypt, tombs dating back thousands of years. In the Mediterranean, cork was used to make buoys to float fishing nets. The Romans, made beehives out of cork, because of its low heat conductivity. The Romans employed corkwood planks in the construction of their homes, a tradition to today in North Africa. Fishermen used cork to create life jackets.

Though the material seems simple in the sense that it needs no additives outside of its natural chemical compounds, cork is actually a highly complex material in its makeup, a complete package in and of itself. Cork has an incredibly unique physical makeup, as it is composed of closed cells containing air, suberin, and ceroids. This makes cork impermeable to gas and liquid, heat and impact resistant, hypoallergenic, and incredibly light weight. Cork’s closed cell structure gives it great versatility.

Cork Trees and Cow, Portugal, photograph by Kim Steele


 Despite its many different uses, for centuries the most faithful ambassador of cork to the world has been the natural cork stopper, that seal of exceptional quality that is still today preferred and demanded by the great wine producers. However, throughout History there have been numerous references to this product and its varied applications. In 3000 BC, cork was already being used in fishing tackle in China, Egypt, Babylon and Persia. In Italy remains dating from the 4th century BC have been found that include artifacts such as floats, stoppers for casks, women’s footwear and roofing materials. Also dating from that period is one of the first references to the cork oak, by the Greek philosopher Theophrastus who, in his botanical treatises, referred in wonder to “the ability that this tree has to renew its bark after it has been removed.”

Vintage Cork Cooler, made in Portugal, photograph by Kim Steele


Wine and cork are two products that have long been companions. Proof of this is an amphora from the 1st century BC found in Ephesus: it was not only was sealed with a cork stopper, but also still contained wine. Later, in the 1st century CE, the Roman naturalist Pliny the Elder made extensive reference to cork oaks in his celebrated Natural History. He explained that in Greece, the trees were adored as symbols of liberty and honour, only priests were allowed to cut them down. In the same work, he notes that cork oaks were consecrated to the god of Olympus, Jupiter, their leaves and branches were used to crown victorious athletes. In Pompeii, the Roman city destroyed by the brutal eruption of Mount Vesuvius, wine amphorae sealed with cork have also been found.



In the 18th century, while in England, the physician Robert Hooke obtained the first microscopic images of cork using a microscope that he designed. In France, the monk Dom Pierre Pérignon, treasurer of the Hautvillers Abbey, began to use cork to seal bottles of his famous Dom Pérignon champagne.

Portugal has been a pioneer in environmental legislation, the first agrarian laws protecting cork forests were enacted in 1209. Later, during the Age of Discoveries, the builders of the Portuguese ships and caravels that set sail in search of new worlds used cork oak wood for the parts most exposed to inclement weather. They claimed that the “sôvaro”, as it was called then, was the best wood for masts and yards–besides being exceptionally strong, it never rotted.

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