This new type of closure became an alternative to natural corks from the beginning of the 1990s because of the increasing occurrence there Korkschmeckers popular. The plugs are usually made from a rubber or Teflon mixture. Three methods are currently used. In the injection molding process, the plugs are cast individually, they are usually hard and very smooth and not particularly flexible. In the extrusion process (extruder = push out, drive), a viscous, foamed plastic mass is pressed through a nozzle in a continuous process. The plugs are then cut off from the resulting strand. In coextrusion (bringing materials together), a core made of a homogeneous, foamed plastic mass is introduced into a tube made of plastic, which ensures radial elasticity. This type is considered the most suitable in terms of flexibility, tightness and uniformity.
In Switzerland, plastic corks have long been a standard and in the New world they are increasingly used. They are available in colored versions, but also in a color that approximates the natural cork. After investigations in the Weinbau-Institut Geisenheim does that sulphurous acid (or sulfur dioxide) reactions with the plastic cork and is broken down relatively quickly within a few years. Studies in Australia have also been faster Sulfur Removal, as well as a too high oxygen permeability, which causes the wines to age faster and to oxidation and can lead to spoilage. In the meantime, however, there are also special plastic corks with a dose oxygen management, The largest manufacturer worldwide in this regard is the company Nomacorc, See also other types of closures below closures,
Image: © SPIEKO bottle caps