There are noumerous enclosures to choose from made from different materials. The traditional natural cork is the best known, and is made from Cork typically produced from the bark of cork trees grown in Portugal. Natural cork is made by punching the cork from a sheet of cork bark.
There is also a couple of cork derivatives, developed for cheaper, and in some applications enhanced performance: Agglomerated cork and Colmated cork.
Agglomerated cork enclosures are made from granulated cork, which typically is a by-product from the cork production. The granulated cork is rinsed.for impurities including TCA, prior to being molded - by 'glue" - into a bottle cork shape. This type of cork is typically not recommended for longer life wines. The time in bottle should be less than 18-24 month. We have had good success with this type of enclosure in white wine. Oxygen ingress is in the same order as screw top closure, largely keeping oxygen out of the bottle.
Colmated Cork enclosures are another type of low cost cork enclosures. This type is most often a combination of a lower grade natural cork combined with finely granulated cork to fill in cracks and cavities in the natural cork. Like the agglomerated cork, the granulated cork is held together by glue. Life-span of this type of cork enclosure is specified to be in the same range as the agglomerated cork of up to a couple of years. We have had less success with this type of enclosure. In one case the glue failed and partially dissolved the cork tip,
The photo above shows an agglomerated cork, after 5 years in a bottle. The wine was well kept in the bottle. The cork shows some signs of change in structure, but this change did not affect the wine.
Looking at alternatives to cork enclosures we have : Synthetic cork, glass corks and screw tops.
Synthetic corks are attractive as they appear and behave very much like natural corks. That means that you will not need to reconfigure a bottling line, both natural and synthetic cork can run on the same line. Oxygen ingress appears to be the highest of any of the enclosures. The extra oxygen in the wine over time can potentially change the character of the wine faster than desirable.
In an earlier post I have a section about synthetic cork.
A sliced synthetic cork. The inside is a foam like substance, while the exterior is a "skin-like" material.
Glass corks were popular a few years back. They are shaped like a traditional bar top cork. I do not have real experience with this type, other than from opening a few bottles with glass corks. A convenient feature of glass corks is that no corkscrew is required to open the bottle, while the bottle in unopened condition will appear similar to a natural cork bottle. As with screw tops this type requires a different line configuration than the natural and synthetic cork types. Oxygen ingress is very low, some measurements show a close-to-zero oxygen ingress. If I were to suggest a use for this, I could think of certain types of white and rose wines.
Screw tops are becoming more and more accepted for wine. It is an ideal type of enclosure for wine by the glass etc. The bottles are very easy to open. The cost of screw tops is lower than natural cork. Oxygen ingress is low, which means that wines sensitive to oxygen will benefit from this type. As with glass corks this requires a difference bottling line configuration. I would not hesitate to use screw tops for white and rose wines, as I think the wine will keep better compared with natural cork.