How Diam Is Advancing the Wine Closure Market

photo by Philippe Laurent for Diam

photo by Philippe Laurent for Diam

Despite all the wine closure options out there, traditional cork remains “king” in most markets, with many consumers associating natural cork with wine quality (save for Australia and New Zealand, who prefer the screwcap). In recent years, however, technological corks have been making headway, with these closures increasing in market share in recent years.

One type of technological cork that has seen their market share skyrocket in recent years is the Diam (and Mytik Diam) cork. Made using traditional cork, Diam seeks to eliminate the issue of cork taint and provide winemakers with a high level of consistency in aging from year to year, all while maintaining all the traditions of a natural cork.

Briefly: How a Diam Cork is Made

First, Diam purchases raw cork straight from the producers, breaks it down into tiny particles, and runs it through their patented cleaning process: the Diamant® supercritical CO2 cleaning technology that was developed as an exclusively cork purification process. Originally developed in the 1950s by Maxwell House to decaffeinate coffee, the Diamant® supercritical CO2 patent further developed that technology specifically for corks: an industry first.

At a certain temperature and pressure, CO2 lives in this state between liquid and gas, called the “supercritical” state. When CO2 is in this supercritical state, it can penetrate deep into cork and remove the TCA compounds responsible for cork taint, as well as other compounds that may negatively influence the wine.

photo by Becca Yeamins-Irwin

photo by Becca Yeamins-Irwin

After a sifting process to remove any dust or wood particles (keeping only the suberin, the main component of cork), the cork particles then undergo the Diamant® supercritical CO2 cleaning process. After cleaning, the TCA-free cork particles are put back together using another patented technology that uses food-grade binding agents and food-grade microspheres, both of which have been specially notified by the FDA, to provide elasticity and consistency in the finished corks.

Focus on Sustainability

In addition to eliminating the issue of cork taint and promoting consistent aging in every cork, Diam also places a strong focus on sustainability.

Production of the traditional cork is said to be highly sustainable. Since a single cork tree is harvested once every 9 or 10 years, and each tree lives for about 200 years, cork forests can provide cork for the industry for a very long period of time while at the same time providing a thriving ecosystem for other organisms and plants.

According to Dominique Tourneix, CEO of Diam Bouchage, “cork is at the heart of a sustainable economy. As a renewable and natural raw material, the cork is part of an ecosystem whose diversity and economic value are essential for the Mediterranean basin”.

Utilization of the Entire Cork

Imagine a rectangular piece of cork. Now, imagine punching out small cylinders from that piece that will eventually become an individual cork closure. You can imagine that there are still pieces of cork present in the original rectangle that didn’t get punched out into a cork cylinder. With traditional cork, these extra bits are discarded. However, because of Diam’s method of grinding down the cork into small particles, they can use the entire piece without discarding any of the cork.

Supercritical CO2 treatment: “Green Chemistry” and the Reuse of CO2

“Green Chemistry” is defined as “the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and application of chemical products” (Green Chemistry: Theory and Practice, Anastas, P.T. & Warner, J.C., Oxford University Press, 1998). For Diam, the use of their patented supercritical CO2 treatment for cork production is green chemistry, since the process does not use any solvents or other harmful chemicals.

Since the supercritical CO2 treatment is a closed process, that means Diam can “trap” the CO2 used and recycle it to be used repeatedly, therefore, little CO2 is lost or wasted.

cork being punched out, photo by Becca Yeamins-Irwin

cork being punched out, photo by Becca Yeamins-Irwin

The first closure company to proactively evaluate their carbon footprint

In 2004, Diam became the first closure company to proactively evaluate their own carbon footprint. As a result of this evaluation, Diam was better able to focus on and address areas where they could help improve their carbon footprint even more.

In 2007, and then further developed in 2009, Diam implemented a company-wide environmental policy to help further reduce their impact to the environment and to maintain accountability in the sustainability efforts of the company by closely monitoring and reporting these impacts every two years.

Control of Energy Consumption and Greenhouse Gas Emissions

To keep an eye on energy consumption and their carbon footprint, Diam performs and publishes its Greenhouse Gas Emissions balance every two years. Additionally, in 2015-2016, Diam underwent a Life Cycle Analysis for two of their closures (Diam and Mytik Diam), to gain a better understanding of how production of their products impacts their carbon footprint, allowing them to target specific areas of production for better greenhouse gas reductions across the board.

Reduction of Production Waste: Cork Dust and Promotion of Cork By-products

During the molding process, there can be a bit of dust (Diam’s main by-product) that is created when the machines cut around the edges of the raw cork to shape the final product. Diam captures this dust and then burns it to produce their own energy at their production plant in Spain.

Additionally, any cork that doesn’t live up to their standards gets discarded off the production line. Plus, any corks taken out of the line for any reason cannot be put back into production, as they have now been contaminated. Instead of just throwing these “rejected” corks in the trash, Diam sends them to cork recycling companies like Diakonie Kork in Germany, where they use these recycled corks to make insolation materials.

cork being tested for quality, photo by Becca Yeamins-Irwin

cork being tested for quality, photo by Becca Yeamins-Irwin

Management of Industrial Risks and Hazards

Diam has accident prevention methods in place, dust combustion boilers that are equipped with technology to reduce risk of explosion, noise control, and methods to prevent an accidental release of waste materials into the water.

Additionally, all staff are trained regularly on industrial risks and possible emergency scenarios, and Diam performs regular emergency simulation tests.

Advances in Sustainable Cork: Origine® by Diam

In addition to all the measures taken by Diam to reduce their carbon footprint, this year they have introduced a new cork (Origine by Diam®) that is available to those wineries looking for an even more sustainable approach to their wine closures. What makes this cork a more sustainable option is: 1) the binding agent used is made of 100% organic polyol, which is completely plant in origin and renewable and 2) it utilizes a beeswax emulsion, which is 100% natural and, in turn, helps support and protect the most important pollinators for our food supply and for natural biodiversity.

Looking Ahead

photo by Becca Yeamins-Irwin   

photo by Becca Yeamins-Irwin


Through their proactive carbon footprint analyses to their investments in research and development for more sustainable products like Origine by Diam®, Diam appears to be a company well committed to sustainability. From 2006 to 2010, Diam reduced its carbon footprint by 15%, starting from emissions of 21.2g CO2/unit and dropping to 18.0g CO2/unit. Additionally, while the total production of Diam closures has increased by 80% between 2010 and 2016, their overall carbon impact has only increased by 55%, indicating that their commitment to sustainability appears to be working.

Though the increase in carbon impact is small compared to their overall production increases, Diam remains committed to further reducing their carbon footprint by improving production efficiency as well as developing new products that are sustainable, natural, and better for the environment overall.

Disclosure: The author was invited to a paid press trip to Diam in France. The contents of this article were not influenced by Diam.

Sources/further reading:

Diam website

“Keeping an open mind on closures” (Wine Intelligence)

Green Chemistry: Theory and Practice

Diakonie Kork