August 2010 Issue of Wines & Vines

Glass Closures Break Through

Price, appearance and TCA prevention help build acceptance

by Peter Mitham

  • Glass closures are stylish and popular with consumers.
  • Wineries appreciate security of the seal.
  • Lower pricing promises to be an ­incentive.
  • Reduction carries potential for concern.
Transparency is what wineries should be focusing on these days, if the conventional wisdom of the Twitteratti and other social media and marketing types carries any weight.

One area where a few wineries are finding it especially cool to be transparent is closures. Since the debut of the Alcoa Vino-Seal stopper seven years ago (it’s marketed under the Vino-Lok name in Europe, although both names fall from vintners’ tongues in North America), dozens of wineries have expressed interest in the product.

Because the closure is glass, it’s recyclable and lends weight to wineries’ claims of being environment friendly. The glass stopper held in place by a resin ring offers an alternative to cork without all the dangers of trichloroanisole (TCA) and cork taint. The closure not only blocks the bottle’s mouth, but the risk of chemical contamination as well.

And then there’s the transparency of the glass, which makes for a slick presentation that customers accustomed to the traditional closures don’t expect.

“It’s different, it’s fresh,” says Maria Stuart, co-owner of R. Stuart & Co. Winery in McMinnville, Ore. “Everybody I talk to about it in the trade—in particular in restaurants, etc.—is very excited. They’re very enthusiastic about it.”


Reducing risk before bottling

Cork-stopped bottles may face the risk of trichloroanisole (TCA) contamination, but bottles sealed with glass stoppers may suffer reduction.

While wineries such as R. Stuart want a secure seal that eliminates risk and unwanted variations in wine, an airtight seal can cause sulfur in the wine to reduce, thanks to a lack of oxygen. Originally identified in Australia in screwcapped wines in 2001, the phenomenon is now associated with wines bottled under highly anaerobic conditions.

Vino-Seal stoppers, which Alcoa research claims have an extremely low oxygen-transmission rate of 0.006 cc per day (vs. 0.097 cc per day for natural cork and 0.04 cc per day for synthetic cork), allow stability, but R. Stuart winemaker Rob Stuart says vintners have to know the effect bottling will have on their wines.

“Are you sealing too well, or are you not sealing enough? Do you want some rate of oxygen exchange with the outside world, or do you not? Many people who bottle wine don’t think about that until they have a problem,” he says. “You need to know your wine, know your closure, know your bottling equipment and know the bottles that you’re putting the wine in.”

When it comes to fighting reduction, he says winemakers must address the question before bottling.

R. Stuart is in the process of shifting all of its reserve-tier wines to glass stoppers. Its small run of late-harvest Riesling was released under glass earlier this year, and the remainder (approximately 2,400 cases of Pinot Noir from the 2008 vintage) will follow in October.

R. Stuart is one of dozens of U.S. wineries that have followed Napa’s Whitehall Lane Winery and Oregon’s Sineann Winery in adopting the closure. The largest user is Calera Wine Co., which has bottled more than 70,000 cases with the stopper (see Laurie Daniel’s interview with Calera winemaker Josh Jensen in Wines & Vines, July 2010).

The current generation of the stopper is about 1.125 inches in diameter. A Dupont-made Elvax resin gasket seals the bottle and holds the stopper in place. A range of four bottle molds has been designed for use with the stopper.

However, introducing the stopper to wineries presents challenges, in spite of its merits among shoppers as a stylish and popular closure.

Jensen says that Calera hasn’t received a single complaint from consumers, but he notes there are no applicators that allow a glass stopper to be as standard or interchangeable a closure as, say, a cork or screwcap. Calera, instead, employs someone to place the stopper atop each of the bottles as they move through the bottling line.

The obvious labor cost could be a challenge for smaller wineries.

Jon Casteel, who operates a mobile bottling line in Oregon and advertises his capacity to handle the Alcoa stopper, says that of the five wineries he’s worked with using the glass stopper, just one is embracing it as a standard closure.

To accommodate glass stoppers, Casteel purchased an adaptor at a cost of approximately $3,000 from Italy’s Gruppo GAI, the manufacturer of his bottling line. The adaptor sits on the corking head and makes application of the stopper a cinch.

R. Stuart puts stoppers on by hand, then tamps them in with a rebuilt GAI monoblock bottling line that it also uses to apply screwcaps. R. Stuart intends to acquire a magazine for the corker head similar to what Casteel uses to facilitate insertion of the Vino-Seal stoppers, but winemaker Rob Stuart’s main concern is that the bottles be pilfer-proof.

Indeed, bottle security is one of the main points militating against widespread adoption of the stoppers, according to Casteel. The closure is almost too simple, like a car with push-button ignition. It’s clever, but almost so advanced that you can’t help but feel you’re missing a step.

“Most people don’t feel comfortable just putting the stopper in the bottle and not having anything additional to help support the closure,” Casteel says.

A glued-on capsule is recommended to ensure the security of the seal, but not everyone uses it. Indeed, the primary purpose of the capsule seems to be to highlight the product’s integrity and to complete the overall presentation of the bottle.

While the Vino-Lok closure offers purchasers outside the U.S. a couple of options for clothing the top of the bottle, U.S. wineries don’t have the same run of choices. And the nakedness cries out for coverage, even if only to demonstrate that the bottle is as intact as the day it left the winery.

Rob Stuart modifies his system by placing a tin capsule over the first-generation Vino-Seal bottles and stoppers he uses. (While more aesthetically appealing, stoppers in the product’s second generation have tended to pop out even before capsules are applied.) The noise during bottling is more than usual, but the result is a clean top that Stuart says looks great.

“That foil is on there just like it’s on a cork bottle,” Stuart says. “I’ve resolved the pilfer-proof liability issues, and I have a closure that works. Without much retrofitting in my winery, I can do this glass stopper thing and survive.”

Another factor against earlier adoption, and one mentioned in most conversations about glass stoppers prior to this year, is the price. It just hasn’t been competitive against cork and alternative closures such as Stelvin screwcaps. Coupled with the aesthetic issues associated with the capsule, several wineries opted against it.

Or, as Patty Bogle of Bogle Vineyards in Clarksburg, Calif., told Wines & Vines last August, after Bogle’s own experimentation with Vino-Seal: “We liked it very much. However, the cost per bottle was way too high for our price-point, and it still requires a capsule to keep it on.”

That changed this spring when distributor Encore! Glass of Benicia, Calif., announced it would slash the price of ¬Vino-Seal stoppers by almost half, to about 41 cents each. The price was suddenly competitive with cork, giving wineries a new reason to consider the glass stoppers.

But in Canada, Working Horse Winery of Peachland, BC, isn’t as concerned about price as it is about wine quality. The aesthetics of the Vino-Lok stopper are appealing, and even without a capsule Hainle says the stopper stays firmly put. Working Horse winemaker Tilman Hainle hasn’t encountered any problems, which the 2-year-old winery uses solely for its white and ice wines.

“I really liked the concept of that glass stopper, because it provides as close to a perfect seal as I’ve seen in the industry,” he says. “We encourage people if they don’t finish a bottle to put the stopper back in, and they have a great seal standing up, lying down, it doesn’t matter.”

The cost to Working Horse, which produces less than 1,000 cases of wine per year, is about $1 per stopper. That’s about the same as the high-end natural cork Hainle selected for Working Horse’s red wines, which he wants to experience the small amount of oxygen a cork lets through.

With his other wines, however, Hainle wanted a secure seal.

He had seen an article in Wines & Vines mentioning the stopper’s use in protecting delicate German wines such as Riesling, and was intrigued. Hainle, credited with making some of best the best Riesling in British Columbia during his tenure at his family’s winery, was keen to try the stoppers when he launched Working Horse in 2009.

“I really like the idea of an inert, very, very secure seal on the wine so far as oxygen is concerned,” he says. Vino-Seal is superior to screwcaps in his opinion, because the wine makes minimal contact with the seal, which is effectively like the o-ring gasket used to seal homemade preserves in their jars.

“The little bit of seal material that is exposed to the wine—I believe it’s high-resistance silicone—providing essentially an o-ring seal on the bottle, I’m much more comfortable with that than the polylaminate inserts that you find in screwcaps or any kind of synthetic or cork alternative.”

The security of the seal also appeals to Rob Stuart, who says that of the alternative closure systems that exist, the Vino-Seal appears to offer the greatest security for his top-tier wines. He’ll continue using screwcaps for R. Stuart’s popular Big Fire tier, however.

“Whatever I put into the bottle, I want that to be what I put in the bottle—not different because from one cork to the next there’s some variance,” he said of his shift to screwcaps and glass. Glass, however, trumps screwcap in the popular imagination when it comes to rivaling the kind of closure cork provides.

“I’m aware of all the opposition to anything but cork,” Stuart said.

Our Northwest correspondent Peter Mitham is a freelance agriculture writer based in Vancouver, B.C. Look for his weekly dispatches at Headlines. Contact him through


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