We put our wine bottles in the recycling box but what about the screw tops on the bottles? Where should they go?

To safeguard the bubbles in his sparkling wine, a French monk called Dom Perignon started putting corks into bottles in the early 17th century. A US company, Supreme Corq, began marketing plastic stoppers on a large scale in the 1990s. In recent years, wine producers, especially in Australia and New Zealand, began using screw tops.

About 20 billion wine-bottle stoppers are produced each year worldwide. Wine bores argue the merits of the various types but rarely discuss how the different stoppers can be disposed of or recycled.

A screw top is usually made of aluminium alloy. Though the production of aluminium involves huge amounts of energy, it is relatively easy to recycle. However, inside the alloy screw top is a sealant, usually made up of oil-based compounds such as polyethylene, polyvinylidene chloride (PVDC) and a paper called white kraft. All these act as barriers, preventing oxygen, chemicals or moisture entering the bottle.

You can undo your screw top from the bottle and put it in the bin with the aluminium cans, foil and other materials but that is no guarantee that it will be recycled. The compounds and chemicals that go into making the sealant contaminate the recycling process: a lot of those screw tops will end up in landfill.

Environmental groups, including the WWF, are in favour of cork stops. The cork oak forests of the Iberian Peninsula and North Africa are rich in biodiversity. The cork oak is one of Nature’s great recyclers — shedding and growing its precious, spongy, bark every ten years or so. Tens of thousands of country people depend on cork for their livelihoods. The big cork companies, based mainly in Portugal, are also on the offensive against upstart plastic and screw-top closures. They claim that independent observers have found that CO 2 emissions during the production cycle of a screw top are 24 times higher than those emitted when producing a cork stopper, while plastic stoppers create ten times more CO 2.

Cork producers argue that old bottle stoppers can easily be recycled and used for everything from flooring to insulation, to gaskets on machinery and packaging.

And then there are all the arguments about which closure method is best for the wine. It’s all very confusing — enough to make you uncork, unscrew or de-plastic another bottle.

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greenandconfused@thetimes.co.uk

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