There are a variety of closure types in the wine industry. The most common closures are natural corks, closures made from ground-up natural corks (such as agglomerated and micro-agglomerated closures), screwcaps, and synthetics. (See explanations of some of these closures here.) How sustainable and recyclable are each of these closures? Moreover, is that even the right question to ask?
In looking for answers, I spoke to individuals at major closure companies, recycling companies, Seattle Public Utilities (SPU), and intermediary businesses. Here is what they had to say, presented as a series of questions and answers.
Are natural cork stoppers and closures made from ground-up natural cork sustainably made?
Yes. Cork comes from tree bark, where the bark is periodically stripped and then regrows. Some of these corks are made into natural corks, where the cork is punched whole from the tree bark. Others are ground-up into micro-agglomerated or agglomerated corks, where ground-up cork granules are held together by some type of binder.
These closure types are sustainably made. However, some consumers do not necessarily understand that.
“When I started at this organization, the general populace believed a number of things, and probably the most important is that the trees are being cut down to harvest cork,” says Patrick Spencer, executive director of the Cork Forest Conservation Alliance, a 501c3 non-profit, forest conservation organization. “That’s not true.”
Can natural corks and closures made from ground-up natural cork be recycled?
No. Natural cork closures cannot be recycled. That is to say, you can’t take a natural cork, put it in a recycling bin and expect that it will magically reappear some day in a subsequent bottle of wine. Natural corks can, however, be upcycled. In this case, the closures are collected and turned into something else.
How are natural corks and closures made from ground-up cork upcycled?
Natural corks and closures made from ground-up, natural cork cannot be upcycled through municipalities. There needs to be one or more intermediaries.
Companies like Recork and Cork Reharvest have recycling programs across the U.S. Here consumers take their corks to a drop-off location, which is usually in a wine store or wine department.
There are also private companies, like Seattle-based Ridwell, where consumers pay a subscription fee to recycle items that municipalities do not. For Ridwell, one of these items is wine corks.
“What we’re trying to promote is people using a sustainable, renewable stopper,” says Gerrine Pan, vice president of partnerships for Ridwell. In January of this year, Ridwell collected 20,000 pounds of cork across six markets in different states.
PCC Community Markets, a Seattle-based grocery co-op, partners with Ridwell to offer cork recycling in two of its stores. Sustainability manager Stephanie Mock says consumers love it.
“You don’t typically see people get really excited to recycle things, but when someone comes in with a giant bag of corks, they’re smiling,” she says.
What happens after natural corks and closures made from ground-up natural cork are collected?
After corks are collected, these closures are further consolidated. Ultimately, they are sorted, and the natural corks and corks made from ground-up cork are molded into something else. This might be a trivet, a sole of a shoe, a cork board, or the like.
Can all closures that are made from natural cork be upcycled?
Yes. As noted above, there are various different closures made from natural cork. These include micro-agglomerated corks (such as DIAM), agglomerates, closures with natural cork disks on each end with ground-up cork in the middle (1+1s), and others.
“All of them are useful,” says Patrick Spencer at the Cork Forest Conservation Alliance.
Can natural corks be composted?
“Corks and other items that are 100% organic and natural can be challenging to process at compost facilities,” says SPU’s Pat Kaufman. “Like bamboo chop sticks or tree root wood, not everything breaks down in one pass through the facility.”
The final stage of the compost process at SPU is passing through a series of screens that range between ½ to 1 inch. Corks will not pass through this. So if you put corks into your compost, they will eventually find their way to landfill. Instead, bring the corks somewhere to be upcycled.
Are synthetic cork closures sustainably made?
Some are. Many wine corks globally are made from some synthetic type of material. Whether they are sustainably made or not comes down to the source material and the production method.
In the case of Nomacorc, a popular synthetic closure made by North Carolina-based Vinventions, many of the closures are made from sugar cane. The company claims their production has a negative carbon footprint when the entire lifecycle of the product is taken into consideration. (NB: Vinventions also sells screwcaps and micro-agglomerative closures.)
Can synthetic closures be recycled?
No. As with natural corks, synthetic corks can’t be recycled and show up again in your wine bottle. As with natural cork, they have the potential to be upcycled.
What happens after synthetic closures are collected for upcycling?
In the U.S., Vinventions partners with Total Wine & More to collect its synthetic closures. “Most of the stores have it. We pay for it,” says Mike Clayton, brand manager at Vinventions.
Once collection boxes are full, they are sent to a sorter. Closures made using natural cork are sent to be turned into trivets and other things. The synthetic corks are shipped to a polymer recycler, where they are turned into low density polyurethane (LDPE) pellets. These LDPE pellets are then used to create plastics for non-food grade products.
Are screwcaps sustainably made?
No. Screwcaps are traditionally made from aluminum. Bauxite is the main raw material used in the production of this metal. It is mined, crushed, and goes through a production process that ultimately creates aluminum. This production process has a heavy carbon footprint.
Are screwcaps recyclable?
Generally speaking, not at present. While it might seem possible as screwcaps are made from aluminum, unfortunately the size presents a problem.
For example, in the City of Seattle, only metal caps that are three inches or more in diameter can be recycled. Anything smaller goes to landfill, as the city doesn’t have the technology to sort it at present.
Some recyclers have recommended overcoming this obstacle by crushing screwcaps and then putting them into an aluminum can. However, some recycling systems, such as the one at SPU, are based on size and weight. Putting screwcaps in a can might take something that was previously recyclable (the can) and make it into something that can’t be recycled (the can and the screwcaps).
“A best practice for this strategy would be to drop off at a bulk scrap metal recycle site with the larger can filled and closed so things don’t fall out,” says Pat Kaufman at SPU.
Bottom line, screwcaps are made from a recyclable substance, but there is currently a high barrier to recycling them.
Might screwcaps be recyclable in the future?
Yes. Some recycling systems use magnets that might be able to pull out screwcaps in the future. However, we are nowhere near that at present.
Should any type of wine closure – natural corks, closures made from ground-up cork, screwcaps, or crown caps – be put into recycling bins?
No. For municipalities, recycling wine closures present difficulties for two main reasons. First, there are many different types of closures which are difficult for consumers to tell apart. Second, all wine closures are small by their very nature. For recycling systems that use grates, laser scanners, and the like, that makes it near impossible to mechanically sort them.
“Most closures, unfortunately, fall through municipal sorting,” says Mike Clayton at Vinventions. “Even if you throw it in the right bin, once they sort it into the different materials, generally speaking, they just fall through into what ends up going into landfill.”
What’s the bottom line comparing the sustainability and recyclability of these different closure types?
Summing up, most closure types, with the exception of screwcaps, have the potential to be sustainably made. This, of course, is not the same as saying that they are sustainably made.
Natural corks and closures made from ground-up cork (micro-agglomerates, agglomerates, etc.) have the potential to be upcycled. However, this require consumers to separate the closures and take them to a specific collection center or use a pay-for service, like Ridwell. Many areas in the U.S. have collection centers in place.
Synthetic corks also have the potential to be upcycled but also need to be collected and sorted. These collection centers are, generally speaking, in fewer locations in the U.S. than there are for natural cork closures.
Screwcaps are not sustainably produced, and their barrier to recycling is currently considerably higher. One would have to smash them down and find a place in one’s area that would accept them as scrap metal. That seems very unlikely to happen on a wide basis.
However, it is, in theory, not markedly different than the process to collect natural corks and synthetics. Rather, it’s a matter of the lack of convenient collection centers. (NB: This is a very, very big miss by screwcap companies.)
One could argue, given that all closure types require that they be taken to a specific collection site or consumers must use a pay program, the situation in terms of recycling/upcycling across these closure types is not fundamentally different, at least in theory. It’s a question of practice. Additionally, the reality is that most wine closures are not recycled or upcycled, whether they can or cannot be.
|Closure type||Sustainably produced?||
Can be conveniently recycled/upcycled?
|Closures made from ground-up natural cork (micro-agglomerates, agglomerates, etc.)||Yes||Yes|
While none of these closure types have high rates of being recycled at present, we can say that, over the course of time, natural corks and corks made from ground-up natural cork will degrade and disintegrate. Anyone who has opened up a decades-old bottle of wine can attest to that. We also know that synthetics degrade over a longer time, screwcaps even longer.
Does a perfect closure exist? No. It’s all a matter of various tradeoffs, but some have much clearer consumer and environmental benefits than others.
How do closure companies and other organizations summarize their arguments?
Patrick Spencer of the Cork Forest Conservation Alliance sums up his thoughts on this issue as follows:
“It is important to not focus on the recyclability of a closure but to focus more on that closure’s production, usage, and how that impacts the health of our planet. Look at it knowing full-well that no aluminum or plastic closures are being recycled in the United States.
“If you want to do something environmental, if you really care about climate change, buy a bottle of wine with a cork in it. Don’t buy a bottle with a screwcap because you’re not doing anything to help the planet, nor are you with a plastic closure.”
Mike Clayton, brand manager at Vinventions, summarizes the argument for synthetic closures.
“We take the stance that natural cork is a flawed solution. There’s cork taint, corks are super inconsistent, and they are expensive. If wine were invented today, would you ever even consider carving the bark off a tree, punching corks out of it, and using that to seal your product? You wouldn’t.
“With aluminum, you’ve got a high carbon footprint, high [potential] recyclability. For Nomacorc, you’ve got a negative carbon footprint, but low recyclability because we all know, plastic recycling is not the greatest. Chances are what’s going to improve over time is the recyclability of plastic. The carbon footprint of aluminum is not. You can’t really change it.”
Is closure sustainability and recycling even the right thing to be focused on?
Yes and no. Sustainability and recyclability are no doubt important. However, there are larger issues to consider when looking at wine packaging.
Wine closures weigh an average of about 0.2 ounces. A typical unfilled wine bottle weighs about one pound. This makes the overall weight of a wine cork about 1% of an empty bottle of wine. A tin capsule on a wine bottle weighs about the same as a cork.
We know that glass can be recycled indefinitely. We also know that the vast majority of glass bottles end up in landfill, and part of the reason for that is their heavy weight and high cost to transport if recycling centers aren’t close by. We also know that tin capsules all end up in landfill or are incinerated.
So the largest impact we could make on the environmental footprint of wine’s current packaging is to a) lower the carbon footprint of the glass used by using lighter glass, using glass as close to the winery as possible, and/or using something else altogether and b) figuring out ways to dramatically increase our glass recycling.
Those actions would have a much, much greater impact on the overall footprint of wine’s packaging than considerations about the closure. That said, every aspect should certainly be considered, closures among them.
Excellent detail–thanks for the thorough recap. I was intrigued to learn about Ridwell recently–a common front porch accoutrement I learned about after a move to Minneapolis.
I address other wine components in a blog post from a while back: https://blog.sandbox.loupegraphics.com/2021/07/06/sustainability-in-wine-packaging/
Many thanks for the link Kim Connolly!
Great article. Two points I’d like to add:
Most agglomerated closures (like DIAM) use a binder which degrades into micro plastics, the substances that are showing up in our waterways and oceans and do real damage to the bodies of aquatic animals.
Capsules, like the tin referenced in the article, are not recycled. Since they are purely decorative and do nothing to affect the quality of the wine, the best capsule is no capsule at all – consumers can support the growing winery movement to eliminate capsules from bottles by buying bare necked bottles
Ed Boyce, thanks for the comment and information regarding agglomerates. I’ll look into it.
I’m 100% in agreement regarding capsules. See my article from my time at Wine Enthusiast here: