Raw Material and Industrial Process From bark to bottle

From bark to bottle, cork completes a fascinating journey where humankind, nature and technology are woven together and support each other. The harvesting of cork - always performed by skilled workers who pass their know-how from generation to generation - is just the first step of an extraordinary process of transformation where nothing is wasted.

Cork is harvested every nine years, always between May and August, when the tree is at its most active phase of growth. No trees are felled, and cork is harvested without harming the tree. The process is performed with extreme consciousness and focus, by making a vertical, then a horizontal incision on the trunk and carefully pulling of the cork plank. The cork tree is the only species whose bark regenerates itself after each harvest. The bark grows back completely, acquiring a smoother texture after each harvest. For the cork oak, each ending is a new beginning.

“These mighty and majestic Quercus Suber which, besides being so spectacular, silently donate the best quality of stoppers that preserve in ideal conditions our careful work as wine producers”

Marquis Lamberto de Frescobaldi

A cork oak lives on average 200 years

A cork oak lives on average 200 years. It takes 25 years before it can be harvested for the first time, but this first cork, called virgin cork, is not particularly good. After this first harvesting, another 9 years must pass to complete a full cycle. The trunk is marked with a number, from 0 to 9, which indicates the year the cork was harvested. The life cycle of cork is rhythmic and mysterious. In fact, it’s only in the third harvest - on average, 43 years after the tree was planted - that the cork will have reached the quality required for producing natural cork stoppers.

From the plank to the final product, cork goes through a series of stages that differ according to the type of stopper to be produced. However, in regard to preventive and curative measures, all planks for cork stoppers are subject to the same level of care.

The making of a cork stopper is a fascinating process where human eyes and hands are as important as the most up to date, sophisticated technology. In spite of all the changes and evolution in the industrial process, cork stoppers are still the product of an outstanding alliance between man and machine that has been working out for centuries.

“Wine and cork are products that have emerged from nature and from the history of mankind. They have been united for centuries and have taken a long time to achieve their greatest expression.”

Alfonso Larrain Santa Maria, President of Concha y Toro, Chile

The making of a cork stopper is a fascinating process


Cork planks leave the forest in trucks and are placed on a yard where, for six months, it shall stabilize and develop an even moisture content. Each load is labeled and registered to trace the origin of an individual batch to the forest. Traceability is essential to obtain certification by the Forest Stewardship Council (FSC). Planks are stacked onto stainless steel structures in large concrete areas, at a slight angle, to prevent microbial contamination and maximize air circulation.


Following the resting period, planks are sorted by skilled hands who select the thicker planks - high-quality cork - to be transformed into natural cork stoppers, made of a single piece of cork. The thinner planks will be used to make disks for technical stoppers.


The next step of the industrial process is boiling. Cork planks are boiled in stainless steel tanks. The goal is to remove organic objects embedded in the pores and enable cork to reach the ideal moisture content for processing. At Amorim, an exclusive boiling process called CONVEX also captures and removes volatile organic compounds from the water. Each batch is boiled for an hour in a high technology treatment tank. When the planks are taken out, their volume has increased by 20%, making them more regular and easier to handle.


After boiling, the planks are too damp to be processed, and therefore are again stacked for stabilization in an area with good ventilation. After two days, they are ready to be processed.


The edges of the planks are prepared and the corners trimmed. Based on key characteristics like appearance, thickness and porosity the planks are separated into quality categories. Only good quality planks are selected for producing cork stoppers. Those with defects are sent to be ground and will be turned into other cork products.


The selected planks, used for top-of-the-range - natural - cork stoppers are cut into strips and punched with a machine to extract the cylindrical stoppers. This is a highly precise semi-automatic or automatic process.


The stoppers are separated mechanically and photographed by computers, which classify them based on visual quality. Many cork stoppers are rejected and will be used to make cork granulate for technical stoppers.


A statistically significant sample from each batch is subject to gas chromatography analysis, a sophisticated process that aims to detect undesirable components, namely TCA precursors.


The batches undergo treatment with ROSA Evolution, an innovative system patented by Amorim, which uses controlled steam to eliminate any trace of TCA. Each batch of stoppers is submitted for analysis, and whenever the minimum percentage of TCA is detected, it is immediately returned to the source.


Irrespective of the results of the analysis, all the stoppers in the high-quality batches are submitted to a steam distillation process.


Near the end of the process, natural stoppers are polished for a clean, smooth finish. They are then washed, dried, and stabilized. All these processes aim to minimize the risk of microbial contamination.


The cork stoppers are ready for the finishing touches. After confirming that they meet the client’s specifications, natural stoppers are branded, with heat, ink or laser, all approved by the Food and Drug Administration, and covered with paraffin or silicone to facilitate their insertion into and extraction from the bottle.


Finally, the batches are packed, and the packages are sealed. The cork stoppers are ready to discover the world’s finest wines.

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