Portuguese cork gets wings as stoppers war rages on

LISBON (Reuters) - Making cork fly is easy, just pop a bottle of bubbly. But imagine a plane with wings largely made of pressed cork soaring through the skies.

A man places a prototype cork wing on top of the currently-used plastic wing in DynAero's light plane to verify measurements, in a hangar at the Evora airfield September 20, 2009. REUTERS/Nacho Doce/Files

From aircraft in the sky to the microscopic depths of the cork oak genome, researchers in Portugal are working to ensure a high-flying future for cork -- light, natural fire retardant -- even if demand for traditional bottle stoppers keeps waning.

Stubby, leafy oaks, bark carefully stripped from the trunks, line the road leading to the French-owned DynAero aircraft plant in Portugal’s central-south Alentejo region -- the world’s main cork growing area.

Plane parts designed and molded here could help shape the future of a national industry that employs some 12,000 workers, exports over 1 billion euros ($1.4 billion) a year in cork -- more than 2 percent of total exports -- and helps prevent Portugal’s drying south from becoming a desert.

Portugal’s annual output of 157,000 tonnes of cork is just over half of the world’s total.

DynAero’s desire to build its ultralight two- and four-seat planes from cork instead of plastic seems only natural in such a place, but there is more to it than the material’s abundance.

“Year after year, cork wine bottle closures are getting replaced by new materials. Producers know they have to go to more sophisticated applications,” said DynAero director Philippe Sence, explaining the reasons behind the “Aerocork” project, launched last year jointly with three Portuguese firms.

Among them is the world’s largest cork producer Corticeira Amorim, struggling to recover market share in the bottle stopper market, reduced to 70-75 percent from over 90 percent since the 1990s by the advance of metal screw caps and plastic closures.

With cork industry revenues sliding up to 20 percent during last year due mainly to the impact of the global downturn on the wine market, it is yet unclear how the sector will emerge from the crisis since screw caps notably reduce bottling costs.

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“There’s the global crisis and the sectoral problem -- the attack of alternative closures and bag-in-the-box packaging. Screwcaps are trying to steal market share from both cork and plastics,” said Joaquim Lima, head of APCOR cork industry group.

APCOR is launching a 20 million euro cork promotion programme abroad this year -- its largest ever.

Corticeira CEO Antonio Rios de Amorim said that while the fight to recover cork closures’ market share against alternative stoppers was the company’s top priority, research into new applications was key for future development.

“The Aerocork project is a new area of development for cork composite materials, but it uses the already successful experience in applications like kayak-building,” he said.

The prototype cork plane should be ready this year.


The Aerocork partners aim to replace light porous plastic PVC with cork composite in the fuselage, wings and flaps of light aircraft, where it is coated with carbon fiber sheets.

Far from being a return to the wood-and-canvas planes from the early aviation history, the cork-carbon combination is not only light but possesses fire retardant properties. Shredded cork is already used in the thermal protection coating on the Space Shuttle’s external fuel tank.

In nature, the unique cellular bark protects cork oaks from frequent forest fires. Even in Australia -- one of the main promoters of screw cap use in wine -- last year’s deadly fires in Victoria state have triggered a debate on replacing flammable eucalyptus plantations with cork oak.

Last year’s jump in oil prices that made oil-based PVC too pricey and environmental concerns about PVC output and recycling are also among the reasons DynAero wants a new material.

“We know that after a few years PVC will no longer be used, certainly by us and most likely by others in the industry. It is a nightmare in terms of ecological aspects,” Sence said. “Our idea is to sell cork-carbon parts to other firms in the future.”

Cork is harvested every nine years during the oak’s 200 year lifespan without damaging the trees, making the cork industry one of the world’s greenest and naturally sustainable.

Cork makers use the environmental argument in their fight against artificial closures, and they have the World Wildlife Fund on their side, warning that the switch to non-cork closures could destroy the bulk of western Mediterranean cork forests.


In another pioneering research, Portuguese scientists are working on the sequencing of the cork oak genome, which could improve the quality of cork, eradicate “sudden death” disease in cork oaks and better prepare them to resist climate change.

“Desertification in southern Europe is on the rise and cork oak stands help to prevent it. Knowing the genome, we can select the trees that better resist drought,” said Prof. Candido Pinto Ricardo at Lisbon’s Chemical and Biological Technology Institute.

Since it takes over 40 years to harvest the first useable cork, classic genetic selection works too slow to see and study the results of crossings in a scientist’s lifetime.

“But with the genome sequence, we’ll know if a month-old seedling can produce high-quality cork,” Pinto Ricardo said.

Editing by Paul Casciato