OTHER USES OF CORK

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

It is also used in shoes, especially those using Goodyear Welt Construction.

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

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

Cork is used as the core of both baseballs and cricket balls. A corked bat is made by replacing the interior of a baseball bat with cork—a practice known as "corking". It was historically a method of cheating at baseball; the efficacy of the practice is now discredited.

Cork is often used, in various forms, in spacecraft heat shields and fairings.

Cork can be used in the paper pick-up mechanisms in inkjet and laser printers.

Cork is also used inside footwear to improve climate control and comfort.

Corks are also hung from hats to keep insects away. See cork hat.

Cork has been used as a core material in sandwich composite construction.

Cork can be used as the friction lining material of an automatic transmission clutch, as designed in certain mopeds.

Cork can be used instead of wood or aluminum in automotive interiors.

Cork can also be used to make watch bands and faces as seen with Sprout Watches.

Cork slabs are sometimes used by orchid growers as a natural mounting material

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USES FOR SCRAP CORK

Once the bottle stoppers have been punched out of the cork slabs, there is some leftover cork scrap. This scrap is ground up, molded into large blocks and baked in ovens to make other cork products, such as cork tile flooring and cork message boards.

Cork has been used as bottle stoppers for more than 400 years. It is possibly the best suited material to use as a bottle stopper because it contains a natural waxy substance, called suberin. This substance makes cork impermeable to liquids and gas, and prevents the cork from rotting.

As late as the mid-17th century, French vintners did not use cork stoppers, using oil-soaked rags stuffed into the necks of bottles instead?

Wine corks can be made of either a single piece of cork, or composed of particles, as in champagne corks; corks made of granular particles are called "agglomerated corks".

Natural cork closures are used for about 80% of the 20 billion bottles of wine produced each year. After a decline in use as wine-stoppers due to the increase in the use of cheaper synthetic alternatives, cork wine-stoppers are making a comeback and currently represent approximately 60% of wine-stoppers today.

High-speed flash image of a champagne bottle being uncorked

Because of the cellular structure of cork, it is easily compressed upon insertion into a bottle and will expand to form a tight seal. The interior diameter of the neck of glass bottles tends to be inconsistent, making this ability to seal through variable contraction and expansion an important attribute. However, unavoidable natural flaws, channels, and cracks in the bark make the cork itself highly inconsistent. In a 2005 closure study, 45% of corks showed gas leakage during pressure testing both from the sides of the cork as well as through the cork body itself.

Since the mid-1990s, a number of wine brands have switched to alternative wine closures such as synthetic plastic stoppers, screw caps, or other closures. In some countries, screw caps are often seen as a cheap alternative destined only for the low grade wines; however, in Australia, for example, much of the non-sparkling wine production now uses these caps as a cork alternative, although some have recently switched back to cork citing issues using screw caps. These alternatives to real cork have both advantageous and controversial properties. For example, while screw tops are generally considered to offer a trichloroanisole (TCA) free seal, it is possible to find TCA contamination in a screw cap bottle.  Additionally, they reduce the oxygen transfer rate to almost zero, which can lead to reductive qualities in the wine. TCA is one of the primary causes of cork taint in wine. However, in recent years major cork producers (Amorim, Álvaro Coelho & Irmãos, Ganau, Cork Supply Group, and Oeneo) have developed methods that remove most TCA from natural wine corks. Natural cork stoppers are important because they allow oxygen to interact with wine for proper aging, and are best suited for wines purchased with the intent to age. Stoppers which resemble natural cork very closely can be made by isolating the suberin component of the cork from the undesirable lignin, mixing it with the same substance used for contact lenses and an adhesive, and molding it into a standardized product, free of TCA or other undesirable substances.

The study "Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures," commissioned by cork manufacturer Amorim and made public in December 2008, concluded that cork is the most environmentally responsible stopper, in a one-year life cycle analysis comparison with plastic stoppers and aluminum screw caps.

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PROPERTIES OF CORK

The cork is stripped off during June, July and August using a long-handled hatchet to cut sections out of the bark. These sections are then pried away from the tree. Workers must be careful not to damage the inner layer of the bark otherwise the bark won't grow back.

Cork's elasticity combined with its near-impermeability makes it suitable as a material for bottle stoppers, especially for wine bottles. Cork stoppers represent about 60% of all cork based production.

Cork is also an essential element in the production of badminton shuttlecocks.

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 by-product of more lucrative stopper production, corkboard is gaining popularity as a non-allergenic, easy-to-handle and safe alternative to petrochemical-based insulation products which are flammable and emit highly toxic fumes when burned.

Sheets of cork, also often the by-product of stopper production, are used to make bulletin boards as well as floor and wall tiles.

Cork's low density makes it a suitable material for fishing floats and buoys, as well as handles for fishing rods (as an alternative to neoprene).

Granules of cork can also be mixed into concrete. The composites made by mixing cork granules and cement have lower thermal conductivity, lower density and good energy absorption. Some of the property ranges of the composites are density (400–1500 kg/m³), compressive strength (1–26 MPa) and flexural strength (0.5–4.0 MPa).

Washing the cork -- The cork slabs that are cut away from the tree are boiled and the rough outer layer of the bark is stripped away. Boiling the cork also softens it, making it easier to work with.

Punching Bottle Stoppers 

 From the slabs of cork, holes are punched out to make bottle stoppers. This leaves the slabs full of holes. These bottle stoppers are then sorted and shipped to various destinations. The stoppers can at this time be printed or branded with names or logos.

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SOURCES OF CORK

There are about 2,200,000 hectares of cork forest worldwide; 34% in Portugal and 27% in Spain. Annual production is about 200,000 tons; 49.6% from Portugal, 30.5% from Spain, 5.8% from Morocco, 4.9% from Algeria, 3.5% from Tunisia, 3.1% Italy, and 2.6% from France.

Once the trees are about 25 years old the cork is traditionally stripped from the trunks every nine years, with the first two harvests generally producing lower quality cork. The trees live for about 300 years.

The cork industry is generally regarded as environmentally friendly. Cork production is generally 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 and are a particular habitat in the Iberian Peninsula and the refuge of various endangered species.

Carbon footprint studies committed by Corticeira Amorim, Oeneo Bouchage of France and the Cork Supply Group of Portugal concluded that cork is the most environmentally friendly wine stopper in comparison to other alternatives. The Corticeira Amorim’s study, in particular ("Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures"), was developed by Price water house Coopers, according to ISO 14040. Results concluded that, concerning the emission of greenhouse gases, each plastic stopper released 10 times more CO₂, whilst an aluminum stopper releases 26 times more CO₂ than does a cork stopper.

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

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CORK

Cork is an impermeable buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber (the Cork Oak), which is endemic to southwest Europe and north west Africa. Cork is composed of suberin, a hydrophobic substance, and because of its impermeable, buoyant, elastic, and fire retardant properties, it is used in a variety of products, the most common of which is for wine stoppers. The montado landscape of Portugal produces approximately 50% of cork harvested annually worldwide, with Corticeira Amorim being the leading company in the industry. Cork was examined microscopically by Robert Hooke, which led to his discovery and naming of the cell.

So, why does the cork oak have a thicker layer of cork bark than other trees? The tree evolved to protect itself from the harsh conditions of the forests near the Mediterranean. These forests experience frequent droughts, brush fires and temperature fluctuations. Cork is actually made of water-resistant cells that separate the outer bark from the delicate interior bark. It has a unique set of properties not found in any other naturally existing material. It is lightweight, rot resistant, fire resistant, termite resistant, impermeable to gas and liquid, soft and buoyant. It's these properties that make it ideal for stopping wine bottles and tile flooring. Let's take a look at how cork gets stripped from the tree and processed into consumer products

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