Production process.

The removal of bark from cork oak trees can only be performed by specialists—known as bark strippers—to ensure the tree is not damaged. The process consists of six steps and requires two people per tree.

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After harvesting, the cork is left to stabilize for a minimum of six months before industrial processing begins. This allows the moisture content of the cork to even out. The sheets are stacked on large concrete surfaces or other approved materials, at a slight angle, to prevent microbial contamination and maximize air circulation.

After the stabilization or resting period, the cork planks are boiled in clean, boiling water. The boiling process lasts at least one hour and is intended to clean the cork, extract its water-soluble substances, and make it softer and more elastic. This process allows the gas contained within the cork cells to expand, thereby making its structure more uniform and increasing its volume by about 20%.

After baking, the cork undergoes another stabilization period—this time lasting two to three weeks. This period serves to flatten the planks and allow them to settle.

Once the cork has been stabilized, experienced technicians sort the sheets based on their thickness, porosity, and appearance. The thicker sheets are used to produce natural cork stoppers, while the thinner ones are used to manufacture discs or cork for technical stoppers.

Once selected, the cork sheets suitable for the production of natural corks are cut into strips slightly wider than the length of the corks to be manufactured.

Drilling is the name of the process of drilling holes in cork strips using a drill bit. This results in a perfectly cylindrical cork stopper, cut directly from the cork plank. All waste generated during the drilling stage is subsequently ground up and reused as cork granules for technical cork stoppers.

This process is designed to sort finished corks into different grades, which are determined by visual inspection of their surface. This process can be carried out using electronic sorting machines. To refine the grading, this sorting is supplemented by manual inspection, relying on the human eye. At this stage, in addition to establishing quality grades, defective corks are removed.

After trimming, the corks are washed. This process serves to clean and disinfect the corks. Following washing and disinfection, the moisture content is stabilized, thereby optimizing the cork’s sealing performance while simultaneously reducing microbiological contamination.

When corks have high levels of porosity, they can be sealed. Sealing involves filling the pores on the surface of the corks with a mixture of cork dust obtained from the grinding of natural cork stoppers. A food-grade adhesive is used to bond this mixture. This process is used to improve the visual appearance of the cork and its performance.

After baking, the two outer surfaces (the bark and the pith) are removed from the cork slabs to produce soft, uniform cork sheets approximately 6.5 mm thick. These sheets are mechanically cut into circles—discs with diameters appropriate for the corks to be manufactured.

The bodies of technical corks are made from cork granules, a byproduct of the drilling process for natural cork stoppers. These byproducts are processed into granules of varying particle sizes using mills and density sorting tables, and are then bonded with food-grade adhesive before being individually molded into their final shape.

The discs and agglomerated cores are placed in assembly machines. The discs pass in front of cameras that select the side of the disc that will come into contact with the wine. A mark is imprinted by the machine on the side opposite the cork. This mark is detected by a camera in the assembly machine, indicating that this is the side to be glued to the cork body. The discs are glued to the end of the agglomerated cork cylinder using food-grade adhesive.

After the discs are glued on, the cork stopper is placed in a drying oven to ensure proper adhesion of the disc to the cork body, and then moves on to the trimming stage. Here, the cork stoppers are trimmed to the desired dimensions. From this point on, the washing, sorting, finishing, and packaging processes are similar to those for natural cork stoppers.