Cork, Plastic, or Twist? The Cork Industry Tightens the Screws on Winemakers

More wineries are moving towards plastic stoppers and aluminum caps and away from traditional cork.  Some would say this is unfortunate for a host of reasons.  Harvesting cork is an ancient practice that keeps a cluster of cork trees, which are almost entirely in Portugal and Spain, alive.

More winemakers around the world, however, are turning to synthetic alternatives. Wineries in Australia and New Zealand gravitate towards metal caps because importing cork is expensive.  Some foodies would argue that synthetics avoid cork mold that can taint wine while providing an easier way to seal a bottle—and any neophyte who has mauled a cork while opening a new bottle would probably sympathize with that argument.  While many high-end vintners still use cork, synthetics are still gaining in popularity, so now the cork industry is pressuring the winemakers and distributors to stay with cork for environmental and economic reasons.  The 100% Cork campaign features a Facebook page has over 15,500 members and counting.

Corticeira Amorim, a leading Portuguese cork manufacturer, has launched a web site detailing all sorts of facts and statistics.  The company touts a PricewaterhouseCoopers study explaining that synthetic corks create a carbon footprint exponentially higher than that of naturally derived cork.  Other studies explain that cork taint is overhyped; outline Amorim’s efforts to reduce greenhouse gas emissions; and articulate how cork recycling is increasing and how the results of which are beneficial for the planet.  All these reports and campaigns have the purpose of pressuring winemakers to come turn away from synthetics and return to cork.

The environmental and social impacts of cork’s decline are clear:  cork provides some of the few high-paying agricultural jobs remaining on the planet.  A decline in cork production could devastate cork forests, which house trees hundreds of years old and contain rare ecosystems that would disappear should cork production cease.  While many of us romanticize the Mediterranean (easy to do), much of this region has suffered from drought—cork trees protect local soil from drying out and halts erosion.

The questions for the industry are, how does cork perform compared to synthetics, and will emotional appeals to wine producers resonate and change business practices?  And why not develop other uses of cork?  One quick example: we installed cork flooring in one our bathrooms. Intuitively, one would think cork tiles would lack the durability of wood or tile, but several years later, it looks new and holds up well—even when spiked high heels stomp on it.  Surely there are other uses for this timeless product.  Preaching the emotional and environmental benefits probably will not be enough to halt the decline of cork as a wine sealer—but while that fight is a noble one, the industry could also consider other uses for this tree bark that would keep the industry thriving.

Leon Kaye

Based in Fresno, California, Leon Kaye has written for TriplePundit since 2010. He is currently Executive Editor of 3p, and is also the Director of Social Media and Engagement for 3BL Media. His previous work can also be found in The Guardian, Sustainable Brands and CleanTechnica. You can follow him on Twitter (@LeonKaye) and Instagram (GreenGoPost). He's traveled worldwide and has lived in Korea, the United Arab Emirates and Uruguay.

45 responses

  1. The idea that if we don't use corks, Amorim will be “forced” to cut down all the cork oaks is absurd. It would be like saying that unless builders keep using redwood, we will have to clear cut all the old growth redwood forests to make room for urban sprawl. Amorim and the cork barons can choose to leave the forests alone. They don't have to cut down all the trees. Also, they neglect to mention that they wash the corks with tons of sulfur dioxide, the base material of acid rain.

    1. Thanks for your commment. One of the objectives of the campaign ( & is to raise awareness among consumers about where cork comes from, how it is harvested and its overwhelming environmental advantages over alternatives. For example, cork oak trees aren't harmed or cut down to produce cork. The bark of the tree is sustainably harvested so that these trees can live 300 years or more. What's more, cork is washed with water. One member of the Portuguese Cork Association (our client), Amorim, developed a system called ROSA to wash corks. It “is based on controlled steam distillation whereby steam and water under pressure force out volatile trace compounds within the cork cells.” For more details:

    2. Greenwash,
      As the Director of an environmental nonprofit organization, whose mission is to help save the Mediterranean cork forests, I'd like to offer some information that is might be of help to the articles author and this discussion. The cork trees of Portugal are protected by national law therefore, they cannot be cut down, so the notion that the cork forests of Portugal are going away is not really an issue. Where the treat of deforestation and desertification lies is in the other cork producing countries. If demand for cork, from the wine industry continues to diminish, the cork that is now being produced, in Portugal, for wine closures will shift to other uses. That will cause a major shift in the balance of production from North Africa, Spain, Italy and France. With little use for their cork trees and no government to protect them, they will be cut down and replanted with eucalyptus or other “cash” crops. These cash crops will do little to stop the spread of desertification and will dramatically reduce the CO2 absorption and oxygen production the forest now provide. Not to mention the loss of millions of dollars in income these family farmers rely on and the habitat for thousand if endemic species. There is no one in the cork industry who will deny, that there was a lack of proper and timely response to the issue of TCA. But in the last 6-10 years the cork industry has spent millions on QC, research, manufacturing consolidation and support to the wine making community in order to eliminate the problems. To deny the fact that every major scientific and environmental organization on the planet has placed the Mediterranean cork forests as one of the “hot spots of biodiversity”, seems a bit like a head in the sand situation. To suggest that closures (screw cap and plastic) that are not sustainably sourced, biodegradable, renewable, or recyclable make the wine world a better place, is neglecting the major fact that if we continue to devastate our planet by producing plastics and mining for bauxite there won't be enough fertile soil, clean water or air to grow grapes in. In closing please let me add that our organization is completely independent of the Portuguese cork industry, we represent the all the cork forests of the Mediterranean basin.
      Patrick Spencer
      Director, Cork Forest Initiative/ Cork ReHarvest

      1. Thanks for the giving us the facts hat the cork forests of Portugal can not be cut down. You directly refute what is on 100percentcork's site “The Portuguese Montado, with 730,000 hectares that sequesters CO2 and provides a defense against desertification,” which implies that if wineries stop using cork, desertification may commence. Clearly, that can't happen. Greatly appreciated.

    3. Nobody uses sulfur dioxide to wash corks.Its only pure water or steam.I'm assuming that in reality you are confusing washing of corks with bleaching of corks in which hydrogen dioxide is used,which is a neutral chemical

  2. It's a commendable effort but I wonder if it's too little, too late. The arrogance of the cork industry in the 90's when mold and contamination problems were an issue is mostly to blame for wineries looking for alternatives. I don't mind screwcaps in white wines (for convenience) but I don't buy them on red wines. Likewise, I will not buy a wine that has a plastic cork in it.

    Winemakers don't really know what percentage of problems they will have in their bottles until 2+ years after the wines have been bottled. So, trusting the cork salesperson is very, very important. Unfortunately, there are still shady people selling bad corks in the market and, until those disappear, there is going to be a lingering doubt about what you're buying. In short, the trust between wineries and cork suppliers has taken a deep hit, and only time–and great corks–can fix that.

  3. Thanks for both your comments. I wasn't aware of the facts both of your brought up–and one point I neglected to make was–if the cork isn't harvested–why would the trees die? I've been to Spain but didn't make that region, so I haven't seen for myself. There are so many opinions out there–but I have to say I cringed at Amorim's PR machine. Hmmmmm.

  4. Personally, I believe that anything delivered by mother nature beats all the industrial pollution that it takes to produce anything synthetic. Cork goes back to the earth, once used. Plastic and metal just litter the landscape, what? Forever and ever, amen? Or, they're recycled, using more industrial pollution in the process.

    Last fall, I visited a cork forest in the Alentejo region of Portugal. The symbiotic system of life is amazing… Grape vines stand along side olive trees (which were being harvested at the time, the grape harvest had just finished). Sheep were meandering among the vines, grazing. Cork trees were just off in the distance, being harvested, cattle roam amid the cork trees eating their acorns (cork trees are an oak tree). The harvest trees were marked with the year of the harvest, so farmers know not to harvest them again for the next nine years. It appears to be a miracle of nature, rather then a revolutionary alternative created by man.

    Lately, I've been trying to pull out synthetic corks, and they're getting harder and harder to pull out of a bottle… As a wine professional, I've opened thousand upon thousands of bottles. I just wrote a blog draft called, “Plastic corks are going to be the death of me.”

    My vote… cork.

  5. Wineries buy plastic corks because they're cheap (ie a few cents/cork, as opposed to around 20 cents/cork for an authentic cork). But who pays the 'real' price, ie the price that's not reflected in the cash payment, ie the contamination of the environment caused in the production and subsequent disposal of these petroleum-based plastic corks? We, and our children, and future generations will have to pay to clean up the envirnoment, which companies (like Nomacorc) use as if it were an infinite dumping ground for their effluents.
    If you, as a consumer, can buy a product without the plastic packaging, it's obviously better for the environment. Same applies to plastic wine corks. The world doesn't need yet another plastic product. It contaminated and polluted enough as it is. If you're in a hole, the first thing to do is to stop digging!

  6. Leon, thanks for your reply. The trees continue to grow and the ecosystem continues to thrive if the bark is not harvested. Amorim and others could however CHOOSE to cut them all down, and destroy the ecosystem. It would be Amorim's choice, not the wine consumer.

  7. The 2010 Closure Survey Report in the June issue of Wine Business Monthly will give you a less
    emotional view of what the trends really look like.

    1. Good point. This is one of the reasons for our campaign. We believe that once even more consumers are aware of the overwhelming environmental advantages of natural cork over alternatives, they will act as individuals and as a group to make their preferences known at restaurants, their neighborhood wine store and major retailers.

      A report here ( based on Nielsen data, shows that for the 52 weeks ended Feb 6, 2010, there was annual volume growth of more than 11% among top selling domestic premium brands closed with natural cork, compared with a 1.3% drop for alternative closures. This is just one data set so we’re not drawing any conclusions from it now other than this: perhaps now is a good time to take the Cork Pledge at

  8. Thank you for this commentary. The rapidly growing support among consumers( who are making a pledge ( for cork echoes a growing number of polls and studies ( – especially the footnote) and suggests a disconnect between what consumers say they would prefer (overwhelmingly natural cork) and what's being offered at their neighborhood wine shop, major retailers and wineries. The rapidly growing popularity of organic and biodynamic wines also supports the conclusion that a significant number of wine drinkers care a great deal about sustainable industry and green products, like natural cork.

    That's why the goal of the 100PercentCork campaign is to raise awareness among consumers of the overwhelming advantages – especially for the environment – of natural cork over alternative wine closures.

    Regarding other uses for cork, the cork industry has a long history of developing a wide range of products that use cork, including recycled cork stoppers from cork-recycling campaigns like ReCork ( and Cork ReHarvest (

    Cork is used for everything from construction ( and shoes ( to aerospace ( CorkSorb has even developed a product ( to help clean up oil and chemical spills. Check out this YouTube lab test ( of CorkSorb sopping up oil spilled on water.

  9. Thank you for your response. Although I understand that there are benefits to forests and wildlife, what really matters to me is what I use in my bottles. As a winemaker, I choose cork for reds because of OTR, customer acceptance, and price. However, I only buy from reputable and established cork producers which I know own forests in Portugal, as opposed to all the new arrivals in the Napa Valley who buy raw material from brokers in Portugal or, worse, buy rejected lots and resell them. I really don't need cork trials as another part of my job but that is what I have to do.

    Here is what I suggest you do:

    – go after the disreputable cork dealers who have come into the industry in the last couple of years–these guys are selling bad corks and ruining the industry for the rest of you

    – look into BPA (bisphenol-A) which is a chemical found in virtually all plastics, including plastic corks and other alternative closures and which has been linked to a number of neurological disorders. Make sure that it is not used to coat your natural or composite corks. I may be dropping screwcaps and returning to corks for my white wines because my screwcap manufacturer cannot certify that BPA is not used in the screwcap liner

    Your biggest challenge, though, are the people who are selling bad corks, in my opinion.

    1. No synthetic cork on the market has BPA, nor is it found in “virtually all plastics.” There are other estrogenic chemicals that can come from synthetics (the cork industry ignores those for some reason), but BPA is only used in epoxies and polycarbonates, both of which are rigid materials unsuitable for corks. If BPA is found in wine, it's likely to have come from plastic tanks at the winery, thermal transfer inks, or other exogenous sources, not the cork.

      Endocrine disrupters: actual problem. BPA: not really.

  10. I appreciate the desire to save the cork forests and empathize with the cork suppliers, but someone needs to point out to them that the situation that caused wineries to search for alternatives was of their own making. For whatever reason, the cork suppliers could not or would not listen to their customers and solve the problem. The customers went elsewhere. Lesson for all.

  11. Thanks, everyone, for your comments. Sometimes you write these postings and wonder if anyone reads. As someone who loves wine and travel (often) together, this was a nice change of pace for me. I've learned a lot, and really appreciate the discussion. LK

  12. As a sommelier, Plastic corks are awful, and youthful, fruity white wine loses its freshness far more rapidly than when a real cork is used.
    I have less of a problem with the screwcaps when used for fresh fruity white wine designed to be drunk as young as possible, although they can be victim to 'reductive' flavours and aromas.(sulphurous, or rotting organic notes). Cheaply produced real cork should also be avoided, but the good stuff made properly and cleanly (without use of Chlorine) and used in wineries that exclude all use of Chlorine bleach related products is by far the best option, especially for red wines designed to age in bottle. (Chlorine can trigger the formation of TCA (cause of most cork taint) with naturally occurring fungi spores often present in cork)

  13. Lanie, SO2 or potassium metabisulfite are indeed used for washing corks. Some methods involve pure water and/or steam only, but SO2 or KSO2 are used to lighten/whiten the color of the corks. The cork bark is naturally pinkish and, if you don't wash it down with something else, will remain thus. The more sulfite you use, the whiter the cork, on the outside only, of course.

    1. Hi
      Working in the cork industry I feel the need to clarify the usage of chemicals on corks:

      1. Most natural corks are washed in water+steam along with a sanitizing agent (usually Hydrogen Peroxide – H2O2). Some companies (such as ours) have developed other disinfection systems (in our case a chemical-free combination of steam and microwaves) but none of them uses sulfur dioxide (SO2) for disinfection. SO2 is used in packaging only -see 4.

      2. Normally all corks are branded, with a fire brand or marked with a food-grade ink.

      3. Corks are added with an extremely thin layer of paraffin and/or silicone to make it easier to pull the cork out of the bottle, which are all food grade products similar to those used to make apples shiny in supermarket shelves.

      4. Where we DO use SO2 is when we pack corks in plastic bags, by replacing the air inside with a mix of air and SO2 (máx. 1gram per bag) to prevent microbial development.

      Hope I’ve helped to clarify.

  14. Are there different grading of cork? I noticed that different wines say a Grand Cru and Premier Cru from the same wine maker have different textured cork in different bottles. Just curious.

  15. “if we continue to devastate our planet by producing plastics and mining for bauxite…”

    As soon as you read something like this, turn the BS filter to “high.” These processes aren't even vaguely alike in terms of environmental impact, carbon footprint, or sustainability.

    Plastic corks COULD be made better in terms of extractability, wine preservation, and endocrine disruption potential (the bigger, totally ignored issue), it's just that the few remaining synthetic cork companies are not particularly motivated to do so, especially at the prices that wineries are willing to pay for closures.

  16. Stuart, I was going by what I read on Wikipedia ( and other sources. I understand your point and thank you for the statement. However, I have requested statements about this from two synthetic cork manufacturers and, thus far, neither has been able to supply me with documentation. Much like I request certifications on imported wood for barrels as well as manufacture date. So, until someone can certify that BPA is not used in any phase of production of their “corks”–including from their suppliers–I am not going to consider using them. I'm considering moving away from screwcaps because of this issue, as well.

    I won't even bring up my thoughts on Chinese bottles and potential lead content problems…!

    1. Your cork suppliers are worried about liability in the event of some future exogenous contamination. And of dealing with you if you run a flawed or incomplete test on BPA and it comes out positive.

      I hate pulling the, “trust me, I'm an expert,” but… trust me, I'm an expert. ;-) I invented the coextruded synthetic cork, am no longer in the wine industry nor have any financial interests in it, and am currently running two significant NIH research programs on endocrine disrupting chemicals in plastics. So, no axes to grind except my own desire for accurate information instead of uninformed rumor mongering or propagandizing for fun and profit.

      1. By the way, will your tree bark cork suppliers (especially of twin tops, aggloms, and colmates) give you a “zero BPA” certification?

  17. Stuart, you raise a good point about the chemicals used with corks. As I understand it, natural corks are typically coated with emulsions of paraffin and silicone, sometimes block paraffin. Agglomerated corks are coated held together with glues and latexes, and are coated with one of various polymers. It seems as though every cork company uses a different polymer on their agglomerate corks but, since the corks themselves are manufactured in Portugal, the concept of what binds the bits of cork together is a mystery. I'll dig into this more deeply in a couple of months when I go through another round of buying corks. You pointed out that BPA is used in resins and manufacturing hard plastics but it may be that it is somehow making its way through the chain, so I'll look into.

    1. FWIW, I found it impossible to get an FDA or EU cert for direct food contact for the materials used in aggloms and colmates. So going even further to get a cert of zero BPA… well… good luck. And if you have tanks with epoxy liners, you've got a BPA issue as well.

      Again, I'm not defending the synthetics guys- the lack of innovation addressing the problems of shelf life and extraction (and in the case of one major brand, extractives) is very disappointing (lots of PR, very little real progress, and IME no particular desire to fix things if it will cost money). But as I've said about many politicians, there's so much to criticize, why make stuff up?

      1. Hi.
        I work for a cork manufacturer and distributor and I must disagree with your first paragraph: most reputable cork companies assure that ALL their components are appropriate for food contact (according to EU and FDA standards), and have the certificates to back it up. The risk would be just too high not to do it.

        Our company does it and I’m sure all our major competitors do as well.

        Let me know if you would like to receive more detailed info on the subject.

  18. My entire condo is covered in cork flooring. It's been there 11 years. I have raw cork rolled under the vinyl flooring in the kitchen to provide foot cushioning. I grew up in a Tudor built in the 20s, and it had floors of cork, too. Granted, back in the old days the floors were waxed, but today's cork floors feature layers of poly protection baked in. My floors draw huge compliments from folks. And combined with radiant heat, it's extra comfortable in the winter. Cork rocks!Q

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  20. Cork in a bottle of wine is a tradition and have been for centuries, and now they are bad for the wine? soon taking a crap is bad because the paper should be made out of sand. Leave the cork in is a terrible mistake to put plastic that is worse for enviromental resons than cork of wood. give me a break. Ill stop buying any wine with plastic cork.

  21. While cork seems to be a sustainable option for winemakers and bottling companies, it does not take into consideration the true ecological impacts of the cork industry. The fact that Amorim supports the argument that harvesting cork is necessary for maintaining the rare ecosystems is unclear. Often times when harvesting the cork chemical agents and solvents are used to treat the wood. These practices may have less of a carbon footprint, but the industry still puts more emphasis on harvesting cork than recycling cork. Instead of continuing to support an industry that strips trees of their bark, there needs to be more incentive to consumers and producers to recycle cork and synthetics. By placing a corrective pollution tax on cork harvesting the industry would have more of an incentive to encourage cork recycling to buyers. A corrective tax could increase the use of sustainable practices within the cork industry by making companies pay for the pollution/harm on the environment with each harvest. Since the production, disposal and source of cork is drastically lower in CO2 emissions than alternatives, there is less regulation on the practices and production of cork. With corrective taxes companies would adhere more to the market and buyer’s demand of cork with less emphasis on harvest and more on recycling. There still needs to be a control in the amount of cork harvested by these companies. The alternatives (plastic and metal) are not going anywhere but the landfill or recycling depot, so by placing a corrective tax on the cork industry and more importantly the bottling/beverage industry the market would begin to demand products with less of an impact on the environment. Synthetic corks/stoppers seem most viable from an economic standpoint since most are from recyclable material and less of a distance in shipping. Cork is a great option for supporting the environment and will continue to be used by high-class brewers all across the world but in order to convert the cork industry from exploiting to recycling there needs to be more of an opportunity for consumers to recycle to products they have bought.

  22. I would compare a green to gollum .. low iq self indulgers who produce nothing and think their food and gasoline comes from heaven (the average lefty is an atheist).

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