How cork is made
An illustrated guide to the cork production process, part 3

The corks are also graded visually: these workers are looking for duds.

The very best corks cost a Euro each, or more. This worker is sorting the elite natural corks.

These corks look almost perfect, but they can still harbour TCA, so further quality control steps are needed.

In Amorim's laboratory, gas chromatography machines process thousands of analytical samples a month, checking for taint. 

A gas chromatography machine: they're expensive, but necessary, because cork taint is a problem at tiny concentrations, and this sort of technology (gas chromatography/mass spectrometry or gas chromatography/electron capture device) is necessary to pick it up.

Not all cork is used to make natural cork. One of Amorim's most popular closures is a technical cork called TwinTop, which consists of discs of cork sandwiching a cylinder of cork granules bound together by food-grade glue (known as 'agglomerate' cork). This is the production process of the discs. These are made from thin layers of good quality cork.

These are the discs.

The discs are sorted and the side that is top quality is chosen to be in contact with the wine.

The sorted discs are marked so that the best side is kept outwards when the gluing takes place.

The cork granules used to make the agglomerate are cleaned with a special steam treatment.

The granules are glued together and the agglomerate is extruded in long cylinders that are then chopped to the right length. A disc is glued to each end.

The TwinTops are then sorted by hand

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