Wine Bottle Closures

• Three basic types of wine bottle closures exist: natural corks, synthetic corks and screw tops. Natural cork harvested from a cork tree is the traditional wine bottle closure. Synthetic corks fit like traditional corks, but they are made from rubber or plastic and are easy to differentiate from natural cork. Screw tops, increasingly popular wine bottle closures, look similar to screw tops on soda bottles.

Natural Corks

• Natural cork stoppers have been used in wine bottles for hundreds of years. Bottles with natural corks are the ones that need to be kept on their side so the wine touches the cork and keeps it moist. If a cork dries out, it can shrink over a period of time, allowing too much oxygen to get into the bottle. Excess oxygen will spoil wine and eventually turn it to vinegar.

Synthetic Corks

• Synthetic cork stoppers are made from rubbers or plastics. These stoppers do not need moisture to keep their shape. They will not shrink or swell like natural cork. They can be stored upright, but it's perfectly fine to store them on their side, too.

Screw Tops

• It is becoming more common to find screw tops, even on high quality wines. Many people who are not comfortable using a corkscrew find screw tops preferable. Wine sealed with a screw top does not need to be stored horizontally because the screw top does not need to be kept moist. But, like synthetic corks, it does not harm a screw top if the bottle is kept on its side.

The Problem with the Foil

• Because bottles with natural corks and synthetic corks are usually both sealed with a foil on the top, it's not always apparent which bottles have natural corks and which have synthetic. When in doubt, store the bottle on its side. Screw tops typically don't have foil and are easy to spot.