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Jul 13, 2010 10:52 AM

Clef du Vin--Gimmick or Useful Tool?


Not long ago, I was given one of these gizmos. It's a little alloy slug that looks like copper that's swaged into a stainless steel dipper. The idea is that a brief dunk in a sample of wine (1 second for 50ml) approximates one YEAR of bottle aging. It's touted by the manufacturer and retailers as an easy way to tell if the wine you're tasting today will be worth cellaring, and for how many years before the wine's quality peaks.

I have played with my Clef du Vin for awhile now, and I think there is something to this. It certainly DOES change the overall impression of wines, improving most reds for a few "years", and then the quality falls off rapidly. There is great variability between wines, and repeatability in different bottles of the same wine. Some wines have shown a double-dip, just as the manufacturer claims.

I've even used it to try to "advance" young bottles at table, with a fair degree of success.

I know people debate the reactive chemistry theory (allegedly) involved here, and disagree whether and how the Clef du Vin actually works. But here's my real question: Is there anyone out there who has been BURNED by using this as a buying and cellaring tool? In other words, has anyone bought wine in reliance on it working, and had reason to regret it? If so, why?, cellared too long?, wine never aged as predicted?, tasted worse than predicted?, etc.?


  1. There is an episode of Wine Library TV from mid-2007 where it was put to the test, perhaps worth a watch?

    9 Replies
    1. re: Steve_K

      Thanks, Steve, that vid was interesting. I lack the tasting experience (and budget) to be able to know what a fine 20-year-old Cab noses and tastes like, so I guess I'll take Gary's word for the CDV not duplicating that nose and taste.

      What I have noticed (and what Gary didn't seem to) is a definite trend in overall perceived quality--sort of a sum of all sensory criteria--that usually trends upward with reds for varying numbers of "years", and then a precipitous "bright line" dropoff where all the sensory components disassociate to undrinkability. The only wine this pattern didn't generally apply to was a carbonic-maceration Cab I made.

      I was amazed, based on my experience, that the blush Gary subjected to 50 seconds' immersion didn't get vomited up. I thought he was about to say that the CDV unwound the Ch. Montelena Cab's tannins as the "test" proceeded, but he stopped short and just had a puzzled look on his face. Even so, I think the reasons a 50 year-old white Zin would have died long before then are multitudinous, and therefore it was not a very well-conceived test for the CDV.

      After viewing the vid, I'm still unsure if the CDV is or isn't a valuable tool in assessing wine's maturation in bottle. Common sense tells me that what happens in the bottle is almost a 100% reductive reaction, while what happens in the glass with CDV is an oxidative one. So I'm still scratching my head.

      As a winemaker, I can use all the tools I can find that work, so even if CDV APPROXIMATES a measure of a wine's peak maturation/longevity, I'll use it. But I'm hoping that I can benefit from others' experience with this thing, good or bad.

      1. re: kaleokahu

        <<Common sense tells me that what happens in the bottle is almost a 100% reductive reaction, while what happens in the glass with CDV is an oxidative one. So I'm still scratching my head.>>

        In the bottle it is an oxidative reaction, just a very slow one. The CDV oxidises the wine too, but much more quickly.
        I guess the only advantages of the CDV over, for example, just leaving a glass sitting out to oxidise are that it is practically instant and (therefore) there will be no conversion of ethanol to acetic acid as the process is too quick for acetobacter to make a detectable difference.

        It just seems a little agressive to me, if that's the right word. I tend to consider vintage, tannic structure, acidity and depth of flavour and work on that.

        1. re: Steve_K

          Hi, Steve:

          Sorry if my mind's slowly oxidizing itself, but if it's an oxidative reaction in the cellared bottle, isn't it limited to what little 0-2 is dissolved in the wine plus what's constituent in the air in ullage? If that's the case, wouldn't "shoulder fills" age more quickly and be a cheap alternative to the OxBoxes everyone's using to replicate barrel aging? And wouldn't argon-sparged and counterfilled bottles age less or not at all?

          But back to my core question: [Despite the CDV's aggressiveness, failure to duplicate exact aged taste, etc,], is it a useful tool to assess longevity and peak?

          I would like to know, because I have a logical problem trusting what someone (myself especially!) prognosticates for the future life and taste of a wine based on how it tastes NOW. I'm sure there are professional tasters and octagenarian scions of brokers' and winemakers' families who can give educated GUESSES, but really, when a reviewer writes something like: "best enjoyed in 4 years, drinkable for 12", aren't they just saying "the tannins are heavier and more tightly wound than ideal, and the acidity's a bit high, so maybe you should wait awhile"? What do you think their real success rate is with prognostications like this? Is anyone going back and keeping track how well the reviewers have pegged longevity and/or "peak" analyses?

          Color me a cynic, but I think 99.999% of tasters CANNOT remember (nor is their palate the same) what that fine 12-year-old Cab they're tasting today nosed or tasted like when they first bought the case on release, 8 years prior. Even if they're anal-retentive and take extensive tasting notes to bed with them each night, isn't it still largely By-Guess-By-Golly? I mean, I picture the collector opening a bottle of his prized Chateau Reggie every 3 months. Until it goes south on him, he's gonna be happy,maybe even documenting his Hedonic Calculus. But if he bought 10 cases on Bobby Parker's say so that it'd be good 15 years out, and it's peaked and sounded in 5, he's gonna be PISSED OFF. And what's he learned besides not to trust reviewers' guesses? What does he do in the future, buy the 12-year-old at 2000% markup?

          I know there're no guarantees in any of this, but I'd like to be able to give my customers something more than a wild-assed guess or hearsay.

          Oh, and have you actually tried the CDV?

          1. re: kaleokahu

            The manufacturers of CDV were successfully sued in the UK for making unsubstantiated claims.

            But enough people with good palates have said the little gizmo does change the wine, but often changing it in a detrimental way, making it softer, sure, but also removing flavors -- scalping the wine.

            How the device works is obviously a reaction between the wine and the metal alloy of the device. A dunk of one second (the manufacturer's claim) does something in that one second that changes the wine. To me, the exposed copper is the key. My guess is that the copper is freeing up sulfur in the wine, increasing the free (unbound) SO2 in the wine.

            The measurement of free SO2 is one way that wine is chemically measured for age in the lab. Oxidation, an enzymatic reaction, is another. Turbidity is yet another. Acetaldehyde is an important lab test for wine aging.

            The gizmo doesn't work well: it actually changes the flavors of the wine. It cannot actually soften tannins as that would involve something far more complex than a metal reaction.

            There's a science geek on Amazon who wrote a product review. His guess was also a copper reaction. He did some casual testing, then tried the same test with a shiny copper penny and got the same results!

            Read about the experiment here. Scroll down to the consumer product reviews:

            So save your money. With tax and shipping, the gizmo costs $100. Or you could use a penny.

            1. re: maria lorraine

              Hi, Maria:

              I've read the UK court's opinion. I think the decision went against a DISTRIBUTOR's claims that went well beyond the manufacturer's. It was a regulatory complaint (a la our FTC), and the decision was strictly limited to the puffery that was not substantiated, not a debunking of anything.

              When you say "the gizmo doesn't work well", is that conclusion based on your ACTUAL USE of a CDV? Everyone's entitled to their opinion, but it's nice to know if it's based on personal experience.

              I am also puzzled by your statement concerning CDV "freeing up" sulphur in the wine. As a winemaker, I know how much SO2 I put in, and for reds I want 0.5-0.8 ppm molecular, which calculates out (depending on pH) somewhere in the 10-30ppm free. That active S02 will bind with 02 and other compounds in the wine and barrel, such that free SO2 levels will drop 10ppm per MONTH in wood. Are you saying that the CDV UNBINDS the unstable suphitic reaction compounds (ketonic acids, uronic acids, etc.)? If so, then why--when reds can have 200 or more ppm TOTAL SO2 when bottled--don't CDV-treated samples smell and taste like Hell itself?

              Hmmm..., I always thought the only role enzymes played in oxidation was as a catalyst . But then I also thought acetaldehide was a totally stable combination product. Guess I need more chemistry lernin'.

              Anyway, has anyone yet offered an informed opinion as to whether the CDV is a useful tool to assess longevity and peak? NOTE: I'M NOT, NOT, NOT--and I really mean it--NOT talking about whether the CDV AGES wine like Father Time. There must be SOMEONE out there who can answer that.


              1. re: kaleokahu

                I think the scalping may be a key factor -- the wine is less "obtrusive," with fewer edges. Some would attribute that to age mellowing.

                To clarify and correct: Free SO2 *declines* with age. Guess: Copper *loves* sulfur and the copper in the gizmo grabs onto the free SO2, making it appear that the lowered free SO2 (and diff in flavor) is due to age. The copper may also unbind some bound sulfur -- free it up and pull it to it. But I dunno.
                I can ask the lab.

                1. re: maria lorraine

                  Hi, Maria: "[S]calping may be a key factor to..." WHAT?

                  Folks are missing here that the CDV DOES improve overall impressions of many wines--even good ones. It does so only for a limited number of "years" (the video test of a 30-year trial for a white Zin was farcically long) , and the effect is repeatable for the same wine. It is also DIFFERENT across different wines.

                  Yes, of course free SO2 declines with age, but there is so little free SO2 in a 10 year old bottle (assuming it was added up to a reasonable level at bottling), if the CDV took out that minuscule amount, it shouldn't affect the taste instantaneously. I will intentionally over-sulphur some bottles next week and run some tests. I guess it's DIY around here for empiricism!

                  If anyone has ACTUAL experience with using the CDV, I'd like to know, but for now I'm kinda "linked" out on hearsay and speculation.

                  1. re: kaleokahu

                    Firsthand reports on this board may be difficult to come by, especially for a gizmo that costs $100 and is of dubious efficacy. The lousy scientific explanations by the manufacturer don't help.

                    Lots of similar devices have come out over the years and numerous articles have been written on their efficacy and claims. You may wish to read those. Some of the comments by scientists in those articles may interest you. Magnetism's effect on aging wine is an oft-repeated claim, but I can't see how the effect of a magnet could increase enzymatic aging or alter tannin structure

                    Harold McGee, who wrote "On Food and Cooking: The Science and Lore of the Kitchen" wrote an article in The New York Times about the Clef du Vin and The Wand and their claims to "age" wine.

                    For the taste tests, Mr. McGee was joined by Andrew Waterhouse, a wine chem professor at UC-Davis, and Darrell Corti, a highly respected wine retailer with an encyclopedic mind about wine and food (IMO). Waterhouse thought the loss of sulfur aromas and reduced harshness as a result was all the devices could offer: “A number of sulfur compounds are present in wine in traces and have an impact on flavor because they’re very potent,” he said. “Some are unpleasant and some contribute to a wine’s complexity.”

                    So some of the wine's attractive complexity was removed (hence the scalping comments), but some of the unpleasant aromas were removed also, making the wine less obtrusive (as previously mentioned).In regards to aging, “Mr. Waterhouse maintained that no brief treatment could convert the tannins to less astringent, softer forms, not even an hour in a decanter.”

                    1. re: maria lorraine

                      Interesting article... Completely useless in answering the thread's core question, of course, but it is plain their results with the CDV (what they tried is clear as mud) were inconclusive. I will run my own tests. Check back with me in 10 years. Thanks everybody!

      1. re: Steve_K

        Didya read the part where the international sales rep said it worked by replicating the metals in the air in the wine cellar?

        1. re: maria lorraine

          Yeah - there are a few gems in the thread!

        2. re: Steve_K

          Hi, Steve: I didn't find much useful information in that thread, but thanks, anyway!

        3. First........I watched Gary's video as well prior to purchasing the Clef du vin........for some reason people consider everything this self absorbed guy says is bible (though I have bought several of his must have wines and they were swill)....BUT, it's obvious he did absolutely no reading of the booklet that came along with the Clef du Vin, because it clearly states that you can age the wines from 1-10 years, yet the guy was dipping for 25 and 50 seconds (so no moron it's not going to work because you are not using it as the instructions outlined for you) - I guess he knows better than the creators of the product as well, just another notch in his arrogance belt
          He also included a bottle of low quality wine in his tasting (the last bottle), which he admitted would be a wine you drink immediately as it was not a cellarable wine......yet again the instructions clearly state that low end wines will be unaffected by the Clef du Vin because there is no aging recommended for those wines........
          He bad mouths a product, yet doesn't bother to actually follow how you are supposed to use them........annoying, same as his personality!

          I have used my Clef du Vin on several occassions, to the amazement of everyone who tried the gadget for themselves in my wine circle of friends and wine group...........every single person who tried was absolutely blown away by the performance.
          So, for the masses, I think the product does exactly what it sets out to do..........but there will always be some who follow what a guy like Gary says as truth........for those I say you're missing out on an opportunity to experience something really exciting!

          BTW, the retail is $100, but there are several sites out there selling for as little as $59 for this item that I have seen online

          14 Replies
          1. re: dededode

            When do we stop the numbing chatter, the geeky one-upsperson stuff, and the show-off score-keeping and tampering with what's supposed to be a natural gift, and start drinking with pleasure? At a time when artisanal everything is the touchstone, why would anyone want to spend even 10 cents to play these silly games? Call me clueless, but if my head-scratching skepticism brands me retrograde, fine. I've got a bottle of Dolcetto I want to open.

            1. re: bob96

              Hi, bob: I'm an artisanal winemaker, the guy who started this thread, and the core question posed was whether the CDV is a useful tool for assessing a wine's longevity. Got an opinion on that? Or are you an idle speculator on the issue?

              While you were lusting after your Dolcetto at 2:31 this afternoon, I was scratching MY head (and barrel tasting--with pleasure), wondering what "natural gift" we'all here have tampered with to get your goat. And please stop calling yourself a clueless retrograde--I find it so numbing.

              1. re: kaleokahu

                Thanks for the reply. I'm proud to be a speculator, if not exactly idle. I have no opinion on the device because I've never used it, don't fully understand the chemical basis for its organoleptic predictions, and, finally, doubt that even highly accurate output would, in the end, be a net gain for our enjoyment of wine.

                My opinion is also that the core question is one that both never need be posed and one that can never be fully answered. How does one ever know definitively about ageing potential until, well, a wine has aged and been tasted? With so many variables, so many changes (including in one's own palate and sensorium)? How can you record an assessment using this device and then, years later, assess that assessment? What have you learned? Or how have you enhanced anything? If you're laying wine down, for however long, in order to wait for the optimal stage in its life to enjoy it, I'd be completely satisfied with the knowledge of experts, of the wine's history and style, my own experience and best guessing,and the like--shared context. It's always a risk, albeit one tempered by knowledge and experience.

                The gift of wine as a natural product (and no, I don't believe wine makes itself or is an unforced grace) comes to us drinkers from of the vine, the earth, and the winemaker's intelligence, devotion, skill, and vision. Once we agree to buy, open, and drink, the gift is received. I do not care, as some have suggested this tool might be used (I hope I read it right), to change the qualities of that wine once opened. If I like it, lovely; if not, I'll try to understand why. That anyone can talk of "scalping" a wine is beyond me--why not just add table sugar or a drop of flavoring to one's glass to manipulate a wine to one's taste?

                I may be in a CH wine board minority in that I do not care to build a wine cellar, nor do I buy wines that need very long ageing, though I've enjoyed many that do. But I do care about quality, typicity, value, and integrity--at all price points--and pleasure, sometimes deep pleasure, most of all. For me, it's a gamble, joyfully undertaken with winemakers. That transaction, that relationship is the natural gift--however worked through and planned for by winemakers like you. You have my admiration and respect.

                I can see how this tool might appeal to those for whom wine is a major investment, or a professional stake in a competitive marketplace, seen to salve nerves tested by fear of future failure. If it helps someone enjoy wine more, God bless. It's simply useless for me, like expensive varietal glassware or complicated corkscrews, because I just can't see how it does. That's all.

                1. re: bob96

                  Some of the best writing and thinking to appear on the Wine Board in a long while.

                  1. re: maria lorraine

                    Apart from your posts, which I have found very interesting, well researched and informative, Maria Lorraine.

                    The only worry I have about this device is if it would cause me to develop a Clef Palate.

                    1. re: maria lorraine

                      Thanks, Maria. Keep sharing your expertise--I know I've learned much from reading your posts.

                    2. re: bob96

                      Hi, bob96:

                      "[N]o opinion on this device because I've never used it". Coulda stopped there, hmm?.

                      Ever have the deep pleasure of buying a $$$ bottle Bobby P said--6 years ago--would be greatest now, only to find out differently? Ever buy a friend a special bottle that was fantastic two years prior and now is it past its prime? Are these potholes in the hedonic calculus also gifts worthy of your rapturous prose?

                      As a winemaker, I am going to be uppity and ask ANY questions that will make better wine, not out of fear of failure, but to advance the science and art of winemaking. The three years my reds sit in cooperage, and two more in glass are for naught if the drinker isn't pleased X FURTHER years down the line when she opens the bottle. Is it worth buying 47mm premium corks if my wines will peak in 6 years? American (and now Australian) winemakers famously pissed off the French oenoroyalty when they started asking impolitic, pragmatic, empirical questions "that both never need to be posed and that can never be fully answered." And they found a few answers along the way!

                      Mysticism in wine appreciation is something you've cultivated successfully, it seems. I just want to make the best wine I can, and be honest about its longevity. Telling my customers: "It's a gift, an ephemeral natural product, and who knows if we ever step in the same stream twice?" doesn't cut it, even if YOU write my backlabel.

                      1. re: kaleokahu

                        I'll say again that the device may well have great value for those with a serious stake such as yours in the making of good wine that others want to drink. I assume you and other winemakers will routinely take advantage of whatever can assist you in making better wine. And I'll offer again my genuine admiration and respect for the efforts you make. Like everyone else I also hit potholes in the "hedonic calculus" you evoke, even if I never cellar a $$$ bottle or care what Bobby P says.

                        I think I wasn't clear enough about my position as an enthusiast consumer who spends regularly but I suppose modestly for mostly small-scale old world wines. I am neither a collector nor a wine professional. I drink all over the world map, and relish the experiences. I've read enough and learned enough to know what to expect, and when something disappoints, too. Again, I applaud your asking those impolitic and pragmatic questions, and making the answers work for you. We all benefit from that, and from your honesty.

                        1. re: bob96

                          Gee, thanks, bob96.

                          So, I'm genuinely and sincerely curious... What is generally the longest time-from-merchant you keep wine before drinking it? Do you ever buy case lots? When you buy reds in the >$25 niche, how far back in vintage would you say you go, not max but usually? Or do you buy mixed cases on whim and recommendation? Do you purchase a "predictable" wine in vertical flights, so you have a sense of how that wine ages?

                          One of the reasons I ask is that, if you're not going to cellar, you can't expect case lots of the same wine to last very long (unless you drink up each case before buying the next). And if you don't buy case lots, you're kind of stuck paying full-tilt retail for 4+ -year-old wines bottle-by-bottle, and even then when many of the best are sold out.

                          I want you to know that I am not delusional about finding an objective, utterly scientific truth about longevity. I suspect you are right--there are too many variables. But the market I am striving for needs something more than the (swayed/staid/paid) subjective opinions of the professional floggers like Parker.

                          The real promise of something like the CDV--IF IT WORKS--is that even a bottle-by-bottle buyer can buy smarter and cheaper knowing what's (likely) to come with age. And, if something like it is recognized, it will hold reviewers somewhat accountable, and maybe help consumers avoid merchants passing off that 1947 Chateau Reggie to them for two fortunes as "perfectly in its prime" when it's not even close.

                          When I first got into making as a Garage-iste, I promised myself that the effete, snobby, pseudointellectual aspects of sensory evaluation would never control what I did as a winemaker--there are simply too many myths out there that need busting. And wine consumers are carefully trained by Industrial Wine to believe that $$$ wine is better than $$ wine. So I am more like you in cleaving to a "Drink What You Like" philosophy than my posts might cause you to think.

                          You really are a good writer. And graceful, too. Now THERE'S a rare wine.

                          1. re: kaleokahu

                            My reading about the Clef is that has no effect on tannins/benzenes. I cannot see how the Clef could be an accurate predictor of wine aging if that is so. Do you have info on this?

                            1. re: maria lorraine

                              Exactly. Wine ageing is a slow and complex process. How can the clef reproduce or even simulate it? Until somebody explains the science, I put this in the same category as magnetic wine clips and varietal-specific wine glasses.

                              1. re: carswell

                                Carswell and Maria Lorraine:

                                Boy, am I a glutton for punishment! Your latest "I-won't-consider-the-possibility-until-someone-explains-the-science" posts prompted me to crack UC Davis Profs. Amerine, Beg & Cruess' "Technology of Winemaking".

                                Under the heading "Accelerated Maturation", the professors write at p. 289 [caps mine]: "Most procedures involve some induced oxidation:...use of ozone, hydrogen peroxide, CATALYSTS, etc. Many of the treated wines have a 'faded' or 'over-aged' character which is unpleasant... We should emphasisze that THIS DOES NOT MEAN THAT THESE MAY NOT BE USEFUL APPLICATIONS OF SUCH MATERIALS OR PROCESSES UNDER CONTROLLED CONDITIONS...In all rapid aging methods, it must be borne in mind that, while oxygen and heat are the most useful known agents to hasten the aging of wine, either can be overdone very easily...Each wine behaves differently: A GIVEN TREATMENT MAY IMPROVE ONE AND SPOIL ANOTHER...MUCH PROGRESS CAN BE EXPECTED IN THIS AREA." [citations omitted]

                                Addressing copper in particular as a catalyst, they write (at p. 213): "Both copper and iron act as catalysts.", and again at p. 224: "It is claimed that the condensation of anthocyans during aging markedly modifies the oxidation-reduction potential of the wine... COPPER COMPLEXES ARE MUCH MORE ACTIVE AS [sic] CATALYZERS OF OXYGEN THAN IRON OR IRON COMPLEXES.... The main thing to remember is that wine is not a poised system. This means that the oxidation-reduction potential of a wine is primarily dependent upon the state of oxidation of the iron and COPPER PRESENT and on the amount of sulfur dioxide. IN OTHER WORDS, IT IS EASILY SHIFTED."

                                Finally, they say of oxygen's role in aging (at 223): "The minimum [redox] potential found by reduction was lower in old than in young wines...[T]he polyphenolic compounds thus appear to be important in the oxidation and reduction of wines."

                                I'm no chemist, but the above sounds to me like a scientific basis for a role for copper complexes in the accelerated aging of wine, and specifically addressting tannins.

                                So.. the ball's in your courts. Maybe you want to TRY the CDV now? Or are you content with your confirmation bias and that Wine TV guy who wants a 30 year old White Zin?

                                1. re: kaleokahu

                                  The science you cite is not science on the Clef du Vin. None of this stuff about oxidation or your many quotes justifies the use of the Clef du Vin as a wine-aging predictor. The proof -- so far -- is not there.

                                  1. re: maria lorraine

                                    You are right, the wine science I found was not science ON the CDV, but it sure as shootin' sounds like a scientific BASIS for its potential. Are you waiting for peer-reviewed, triple blind, full spectrum tests ON the CDV itself prior to opening your mind to the effects that the alloy actually has on wine? And if the results of those tests omitted diagrammed chemical reactions that fit your (present) theoretical paradigm, could you ever--under ANY set of facts--shift your pardigm?

                                    Given your obvious knowledge of some of the historical advances in oenology where practice long preceded biochemical understanding, I'm a little surprised you aren't more open to some simple empiricism here.

                                    But hey, maybe...quantum mechanics... should be rejected until it's all nailed down, too.

              2. Folks, we've had to remove a large number of very unfriendly posts from this thread. Given that, we're going to lock it.