Synthetic corks come in a variety of styles, from solid rubber to composite corks that wrap a foam core in an elastic outer shell. This two-part product combines the best of both worlds, allowing for a controlled and consistent rate of oxygen transfer through the foam core, while keeping the exterior of the cork firmly in contact with the bottleneck.
Solid plastic or rubber corks, on the other hand, do not allow for oxygen transfer, and tend to fit very tightly in the neck of the bottle. This can make removal difficult and re-use impossible as sometimes you just can’t squeeze the cork back into the bottle. Another drawback with these solid plastic corks is the fact that they lose elasticity with time, allowing air to enter the bottle and degrading the quality of the wine.
In either case, while many of the products used for corks today can be recycled, these corks are generally produced from virgin resources, leading to a relatively large carbon footprint per closure.
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