Natural cork is the traditional method of sealing bottles of wine. Sections of bark from the cork oak are harvested, dried, and turned into corks as we know them.
The key difference between natural corks and screwcaps in wine terms is that corks allow miniscule amounts of oxygen into the wine; this oxygen plays a part in many of the reactions which take place inside the bottle as a wine ages. A screwcap does not allow oxygen in, and hence the aging processes are different.
The world's finest wines are sealed under natural cork, and we believe that the traditional evolution that takes place during the maturation of wine is a major part of what makes wine the most interesting drink there is: it is for this reason that we love natural cork and choose to use it exclusively for our wines.
Screwcaps do have their advantages:
Firstly, they are much cheaper for wineries, running at around 10% of the cost of a quality natural cork.
Secondly (applied correctly) they are consistent, whereas cork (being a natural product) shows variation between individual corks - which in turn results in variation between wines stored in these slightly different environments.
Thirdly, they are free of 'cork-taint', the cardboard, wet wool aroma of trichloroanisole. This compound can be produced in/on corks by naturally occurring fungi in the presence of chlorine, and is detectable at rates of a few parts per trillion. While this has been a significant problem in the industry in the past, things have improved a great deal in recent times.
Our corks are tested in Portugal and again in New Zealand, and our experience has shown a cork-taint rate of less than 1 in 100 bottles - which we feel is a cost outweighed by the benefits of natural cork. We offer a 200% refund on any corked bottle returned to us - we will replace it, and provide an extra one for free.