There are two main types, corks and screw-caps.
Corks are produced from the bark of a cork tree, in the Quercus species. These cork trees can be harvested every few years. Removing the bark off of the trees does not harm them in any way; additionally a new layer of bark will form meaning the cork is a renewable resource. The majority of corks used for wine are produced from trees that grow in Portugal, Spain, France, and Italy. One benefit to cork is the slight bit of air that passes through them over time. This allows older wines to breath. The main drawback to natural corks is cork taint, a bacterial issue in the cork, which makes the wine inside the bottle smell like wet dogs or old wet cardboard. This has been limited though since corks are screened numerous times between the cork tree growers and the cork producers. To keep a natural cork working correctly a bottle must be inverted so the cork stays wet, otherwise the cork will dry out.
Screw-caps are small metal shells that go over the opening in a bottle and twist off without the need for an opener. The main advantage for a screw-cap is the assurance of no cork taint. The down side is the lack of airflow across the closure over time; which is not beneficial to wine that should be aged for numerous years. Screw-caps are the main form of closure in Australia and New Zealand as high quality corks were difficult to obtain when these wine regions started to take off in the late 70’s and early 80’s.
Which closure do you prefer?
-Brian Tomasello 4th Generation Outer Coastal Plain Winemaker Tomasello Winery