Nothing draws the eyes of strangers like the sound of shattering glass. Though the restaurant bar was buzzing loudly, the breaking of my flute was like a tiny, elegant car crash; no one could look away.
I couldn’t either. I watched as the Champagne flowed across the small table, onto my lap and the lap of my companion. I traced its journey as the celebratory liquid dripped into my purse and onto my shoes. Later, as I dug a sizable shard from my palm, I couldn’t help but admire the craftsmanship. Such thin glass, I thought as I sucked the blood from my hand. So beautiful. So sharp.
The sommelier, a friend who had invited me in to show off his new wine program, was understandably annoyed. But so was I. I tend to prefer my Champagne in my mouth, after all, and his expensive and elaborate glassware selection, which exploded after nothing harder than a sharp exhale, had interfered. My thoughts drifted to Miles drinking Cheval Blanc from a Styrofoam cup. Was his the better extreme? He may have missed some nuances, to be sure, but at least he got to taste the damn stuff. And then drive home with dry pants. The luxury!
The fragments of glass on my table twinkled in the candlelight, recalling the beverage they had so recently contained, and I rewound history in my mind. What were the steps that had led to this moment? Were such oversized and overly fragile glasses the apex in the evolution of stemware or simply a silly extravagance? And if the former, was I just an ape batting at progress with my club? What was I missing and, more importantly, how did we get here?
The oldest recorded recipe for glass dates from the seventh century BCE, from the library of the Assyrian king Ashurbanipal. It reads, “Take sixty parts sand, a hundred and eighty parts ash from sea plants, five parts chalk, heat them all together, and you will get glass.” The most remarkable aspect of this text is how little of it has changed. A contemporary glass producer recently shared his recipe: 75% sand, 20% soda ash and lime, 5% modifiers. They may as well have been reading from a stone tablet.
(This is about to get technical—if science makes you nervous, jump to the history section below!)
The most important component of glass is common sand, which is effectively broken-down pieces of quartz. The scientific name for sand is silicon dioxide (SiO2), and it typically makes up two-thirds to three-quarters of the final blend. While it is possible to make glass from only sand (pure silicon crystal is used in the manufacture of superconductor chips, for example), it is more commonly cut. This is because SiO2 has a remarkably high melting point, and the amount of energy required to liquefy it is cost prohibitive.
Lime and soda ash are sand’s most common companions. Soda ash is more officially known as sodium carbonate and has the chemical composition Na2CO3. It was historically extracted from the ashes of plants grown in sodium-rich soil. Soda ash is essential, as it lowers the melting point of the silicon dioxide. It also plays the part of the cook and helps stir the soup! When heated, Na2CO3 breaks down to Na2O plus gaseous carbon dioxide. The CO2 bubbles percolate throughout the molten glass, thereby ensuring a homogeneous mix. If the furnace is too cool, the gas will not escape in time and bubbles can become frozen in the glass. This is commonly seen in antique glass, produced before sufficiently hot furnaces became commonplace during the 20th century.
Soda ash also has an adverse effect on glass, rendering it water soluble. The addition of lime (calcium oxide, or CaO) counteracts that tendency, and also serves to increase durability. These three ingredients combine to form what is known as soda-lime-silica glass, the foundation of the modern glass industry.
A range of other modifiers, generally metal oxides, are often included in small amounts. Their precise ratios will influence the final color and physical properties of the glass. Lead oxide is the most historically common addition; it increases the hardness of the glass, thereby rendering it more suitable for etching and carving. It also increases the refraction index—that is, it adds sparkle. Boron oxide is used in the baking goods industry to increase glass’s resistance to temperature changes, iron oxide can be used to increase heat absorption (it is used in movie projectors, for example), and other metal oxides can be used to add color.
The ingredients are then mixed together in a furnace and heated until they melt and combine, which is where things get interesting. In solid form, quartz has a dense atomic structure, with molecules of SiO2 stacked tightly on top of each other. This is common to crystals, and part of the reason many of them (quartz, diamond, ruby, etc.) are so hard. Once the melting temperature is achieved, the bonds between the molecules break down and the individual SiO2 molecules unstack and randomize, floating around in solution where they become interspersed with Na2O, CaO, and the other modifiers.
Schematic comparison of the atomic-scale structure of (a) quartz and (b) glass (Credit: Dr. James Shackelford and Pearson Education)
Given a slow enough cooling, the natural tendency of the molten glass would be for the SiO2 molecules to revert to their original, highly stable molecular arrangement as a chunk of quartz. To prevent this, molten glass is cooled rapidly, which effectively locks the molecules into the random arrangement of their liquid state. The result is glass as we know it—the vivacious, beloved, but altogether more fragile cousin to quartz.
It should be pointed out that this “cooling” is hardly cold. Glass mixtures used in the creation of stemware need to be heated to 1,200 degrees Celsius or above to melt. The temperature must then be dropped to around 700 degrees Celsius—cold enough to prevent unwanted atomic stacking but still hot enough that the glass can be shaped and molded. Once the desired design is achieved, the object is then annealed in an oven at 450 degrees Celsius for a brief period. This is an essential stage, as the manipulation of the molten glass would have created small strains at the atomic and microstructural level, making the glass brittle. Annealing heats the object right up to the boundary between super-cooled liquid and hard glass. The product is still solid, but hot enough to temporarily relax the structure. This allows the atoms to rearrange into a more stable alignment, thereby increasing durability. The same process is employed when a hammered sword is thrust into a hot fire one last time before being plunged into a cooling water bath.
Glass is a naturally occurring substance that is formed in a variety of ways, most commonly by lightning striking a beach or via volcanic discharge, which results in the glassy rock obsidian. After mastery of fire, the deliberate production of glass couldn’t have been too far behind. Indeed, evidence of glass made by humans dates to before 2,000 BCE in Mesopotamia.
Glass cups and vessels were first produced in Ancient Egypt and Mesopotamia around the 17th and 16th centuries BCE, where they belonged exclusively to the royal and the wealthy. Scholars believe such items were created by pouring molten glass over an earthen mold, a crude but effective practice. A massive jump in quality came around 200 BCE when the Phoenicians invented the blowpipe. This was a major technological breakthrough, and the blowpipe remains a critical element of glass production today. A blowpipe is simply a long hollow tube; the operator, be it human or machine, blows into one end while the other is attached to a glob of molten glass. The result is a hollow sphere that can be shaped as it cools or blown into a mold. This technology allowed for a more nuanced (and safe!) handling of liquid glass than the primitive pour-over technique.
The making of a mouth-blown wine glass, from top left to bottom right: The bowl is blown, generally into a wood mold; the stem is drawn off the bottom of the bowl; the foot, often a separate piece of glass, is added and shaped; the glasses are annealed in an oven; the lip is cut and fortified with a blowtorch. (Illustration by Brandon Lee Wise)
During the Roman Empire, glass became extremely fashionable. According to Chloe Zerwick’s A Short History of Glass, it also became more readily available: “Glass was no longer exclusively a luxury product. In fact, it became more widely used for ordinary domestic purposes during the Roman Empire than at any subsequent time or place until the nineteenth century.” After the fall of Rome and throughout the Dark Ages, glass production faltered in Europe and shifted back to the Middle East and Asia. It came rushing back, however, with the preeminence of Venetian traders during the 11th century. The seafaring Venetians were also responsible for expanding winemaking to the various corners of the Mediterranean and Aegean around this time.
Venice quickly became the locus of glassmaking in Europe, but in 1291, production was banished to the island of Murano, as the giant furnaces were thought to pose a fire hazard to historic Venice. The Venetians attempted to hold tight to their hegemony, forbidding glassmakers from leaving Murano, even hiring assassins to track down and execute escapees. But inevitably, the secrets of Venetian glassmaking spread to other parts of Europe.
Bohemia, a vast swath of Central Europe that includes parts of today’s Austria, Germany, Hungary, Poland, and Slovakia, soon developed a glassmaking industry to rival that of Murano. One of the secrets to its success was the inclusion of chalk, which becomes CaO (lime) when heated. This made for clear and durable glass that stood in contrast to Murano’s more colorful, sometimes cloudy creations. In addition, as the sand reserves in certain parts of Germany contained a considerable amount of iron oxide, the glasses produced there took on a tint that ranged from green to brown. These shades became associated with wines from the Rhine, a link which lingers today. Bohemian glass increased in renown across the centuries and was especially revered during the reign of the Austro-Hungarian empire in the 19th century. Bavaria remains a center of production today, and many of the major stemware houses produce their glasses in either Austria or Germany.
Sand is heavy and difficult to transport. Were 19th-century Bavarian glassmakers carting it in from the Adriatic coast? Most certainly not. While sand is often imagined as being confined to beaches, sand deposits are widely found across all continents. Dr. James Shackelford's Introduction to Materials Science for Engineers explains that oxygen and silicon are the two most prevalent elements in the earth's crust! Of course, the chemical purity of the sand varies by region.
Following the invention of the blowpipe, it is widely agreed that the next major improvements to the remarkably slow-developing glass industry occurred in 17th-century England. There, several advancements happened concurrently. First, the businessman George Ravenscroft found that the addition of lead oxide increased the brilliance, clarity, and durability of glass. And secondly, the rise of coal furnaces increased the temperature at which glass could be melted and worked. This last development came about rather by accident. In 1615, a law forbidding the use of wood as fuel was passed. This was the height of British colonization, and the military wanted to preserve England’s limited wood reserves for shipbuilding. The popularizing of coal furnaces transformed the glass industry and resulted in thicker, stronger bottles that could withstand the pressure of large amounts of CO2. This then revolutionized Champagne production, and for the first time, bubbles became a regular feature of the region’s wines.
In the latter half of the 1700s, the Industrial Revolution swept across Europe and America, modernizing processes and introducing automation to many aspects of the industry. Glassmaking was not excluded. The continuous furnace was invented in 1867, speeding up production by safely running ovens throughout the day and night. Not having to regularly heat up a cold oven was both efficient and energy saving, and this mode of operation remains the model today. In fact, small companies like Zalto, which do not produce enough glasses to justify running their own continual furnaces, rent space inside of larger factories—much like the custom crush arrangement employed by many small wine brands.
An especially important moment in glass production came in 1903. That year, a machine was developed in America that automated glass blowing. Items formerly mouth-blown and crafted by hand could be completely assembled by machine. The jump in production capability was remarkable. According to Aldo Sohm, sommelier and brand ambassador for Zalto in the United States, “It takes seven people seven minutes to produce one hand-blown Zalto wine glass.” By contrast, the new machinery allowed for several thousand stems to be produced in a single hour. The increased speed, and subsequent lower cost, were essential to democratizing stemware. And today, all but the very highest end wine glasses (such as Zalto, Sophienwald, and Riedel Sommelier Series) are produced using such mechanization.
Hand-crafting glasses at Riedel (Photo credit: Riedel)
Of all the many steps in the evolution of wine glasses, the most salient to today’s wine professionals was the aesthetic leap taken in the 1950s. Starting in 1958, Claus Riedel introduced a series of vessels that were elegant in their simplicity, largely stripped of ornamentation, and—critically—varietally specific.
This was the first time in the history of stemware that a drinking glass was engineered to highlight the nuances of a particular grape variety. Formerly, stemware was aligned exclusively with the aesthetic of the overall tabletop, designs that were typically rather elaborate. Per Dr. James Shackelford’s book The Glass of Wine, “The technology of drinking glass manufacturing continued to evolve through the eighteenth and nineteenth centuries when elegant designs produced with meticulous craftsmanship became an essential part of the dining experience in upper class homes in both Europe and the New World. . . . During that time, the focus was generally on the ornate as an unambiguous symbol of the elegance of wine appreciation.”
Claus’s grandson, Maximilian Riedel, comments on the transition: “Before we went into specific varietal glasses, we produced fashionable glasses. We worked very closely with companies like Tiffany’s. But in the very early 1950s, my grandfather realized that the trend of art de la table was slowing down. He also had a great passion for wine and realized that beautiful glasses weren’t always the best complement.” The line they debuted in 1958 marked such a break from tradition and proved so revolutionary that a set was acquired by New York City’s Museum of Modern Art (MoMA), where it is currently on display.
Two different lines designed in the 1960s by Claus Riedel, representing two eras in tabletop design (Photo credit: Riedel)
Riedel’s aesthetically simple yet functionally complex wine glasses gained in popularity, spurring them to introduce the machine-made Vinum line in 1986. The Vinum line, Riedel’s mouth-blown Sommelier Series, and inexpensive Libby glasses dominated the American restaurant scene as sommelier culture was getting established in the 1970s and ‘80s. Daniel Johnnes recalls, “My first year working in restaurants was 1978, but that was really a tavern. It wasn’t until I got to Plaza Athénée in 1984 that I started using great glassware. And when we opened Montrachet in 1985, we used Riedel. The AP [all-purpose] glass was the Overture red, which was set on every table.”
Johnnes remembers Georg Riedel making the rounds in the 1980s. “He was making a big push in New York, doing all kinds of seminars. They were very compelling performances, and this was right when I was getting serious in the restaurant business.” Riedel’s dedicated consumer and sommelier outreach earned them considerable converts and a lot of loyalty. Per Aldo Sohm, “Riedel didn’t really have any competition for 20 years. They were the main guys in terms of glassware for a long time.”
One of Riedel's glass factories (Photo credit: Riedel)
Sohm grew up in Austria, an hour west of the Riedel factory. He comments, “I came up with those glasses. They put the work and the science into it. There would be no great glasses without the Riedels, and you have to give them full credit for it.” But Riedel’s exclusive grasp could not last forever. The past two decades have seen a growing number of competitors, each with its own point of distinction. Sohm himself represents Zalto, which has won over many sommeliers with its delicate glass (so thin it actually bends!) and attractive, angular shapes. Schott Zwiesel is another contender, set apart through the addition of titanium oxide, which gives the glasses added durability.
Riedel still dominates the market, however, and claims to be the third largest wine glass manufacturer in the world. In response to the increasingly crowded marketplace, the company has doubled-down on specialization and maintained its active educational outreach. “We offer a wide selection to our consumers, of course,” explains Maximilian Riedel, “but behind the scenes, a big part of our business has become customization. A wine region or a big Champagne house or something like this will come to us, and we will work with them to make a special glass.” Their list of private clients includes individual varieties, wine categories (such as rosé), even Coca-Cola, for whom they developed a proprietary glass. With private and commercial products combined, Riedel estimates they currently offer over 700 different glasses.
Riedel’s range is so vast that some companies are deliberately marketing themselves in opposition. “We like to give people a choice but not overwhelm them with choices,” explains Ginger Turner, US distributor for Sophienwald glasses. Sophienwald sells only four pieces of stemware in the country: a white, a Burgundy, a Bordeaux, and a Champagne flute. Gabriel-Glas and MW Jancis Robinson take this model one step further by offering only a single glass. In a similar vein, producers such as Zalto are enjoying success with the “universal glass,” a one-size-fits-all approach to wine drinking.
A limited selection of glassware appeals to both the easily overwhelmed and the spatially lacking—apartment dwellers and many restaurants, for example. It also raises the topic of standardization. If indeed glass shape has a dramatic impact on the sensory impression of a wine, then it logically follows that critics and professional tasters ought to stick to one type of glass when evaluating wines. Wine critic James Suckling is famous for carrying his custom-designed Lalique stems with him wherever he goes. And back in 1970, the INAO addressed this topic through the creation of the ISO standard tasting glass. This glass, pictured here, is as simple and utilitarian as one might imagine; useful, perhaps, for massive industry tastings but unlikely to grace the table of any real wine lover.
Many wine professionals believe that the size and shape of a glass affects a wine’s flavor, but none can quite explain how. Those who ventured a guess during these interviews inevitably invoked the tongue map, that age-old diagram that carves the tongue into tasting zones: sweet in the front, bitter in the back, salty and sour on the sides. One sommelier even suggested that glasses could influence a wine’s flavor by directing it to a particular part of the palate.
The problem with that logic is that the tongue map is complete bunk.
“There is no tongue map for the human,” asserts Dr. Linda Bartoshuk, a sensory scientist at the University of Florida. “The tongue map as we know it originated from a 1940s mistranslation of a 1901 German study.” Though later translations corrected the error, the map has proved a particularly sticky form of pseudoscience, and it continues to be taught to wine students. Dr. Bartoshuk’s lab has studied taste on different tongue areas and concluded that, contrary to popular belief, “you can taste all four basic tastes everywhere there are taste buds. Some variation may occur, but it’s trivial. There was never any empirical data for a tongue map.”
So, if the map is out, then how exactly does the tongue work? According to Dr. Bartoshuk, the surface of the tongue is underlain by a handful of nerves. These nerves transmit sensory information from the taste buds to different parts of the brain; inside the brain, those areas then send inhibitory messages to each other. “It’s like an engineering circuit,” she explains. “It’s a compensatory mechanism to preserve whole mouth taste if you injure your tongue.” That is, when a nerve in the mouth is damaged, tasting capability will not be affected. While the sensory input from that nerve may be lost, its inhibitory effect on the other nerves has also been lost.
By extension, taste can be enhanced by isolating certain parts of the tongue. “Take a strong salt solution. If you dabbed it on the tip of your tongue, it would taste really salty,” says Dr. Bartoshuk, “but if you take a sip and swallow, it appears far less salty than you might have predicted. That’s because when you only stimulate one part of the tongue, you skip the inhibition phase.” While Dr. Bartoshuk admits that she hasn’t yet studied how this phenomenon might relate to wine, she imagines that an expert taster could glean a lot of information by sequestering wine to one part of their mouth and then comparing it to the whole tongue taste.
Dr. Bartoshuk allows that the shape of a glass could potentially influence taste by stimulating just a small area of the tongue, but certainly not by aiming for the “sweet center” of the tongue map, as some in the business have implied. Furthermore, as flavor is the combination of taste plus smell, a glass’s effect on aromatics must also be considered. “Sweet, salty, sour, bitter have relatively little to do with wine,” contends Dr. Bartoshuk. “Most wine tasting is the perception of volatiles. It’s olfaction.”
Scientist and wine writer Dr. Jamie Goode agrees. “The tongue is pretty important for flavor perception for a number of reasons, not the least touch. But we give it too much credit. We think the tongue is detecting a wine’s qualities, but that’s because we localize the sensation of flavor to our mouths. But really, it’s the smell, especially the retronasal smell, that matters.”
The classic do-it-yourself experiment to prove smell’s essential role in flavor is to hold your nose while drinking. Even a casual taster will note the wine’s flavor is considerably muted. But release the nose after swallowing and the flavor will improve. This is because of retronasal olfaction, which happens when a wine’s volatile vapors enter the nose from inside the back of the mouth. “The way you sip, breathe out or in, slurp—all of these things affect the retronasal olfaction,” claims Dr. Bartoshuk.
Orthonasal olfaction, or sniffing, happens via the nostrils. And this is what is most affected by the shape of a wine glass. As Émile Peynaud states in The Taste of Wine, “The relationship of surface area to volume of wine varies according to the shape of the glass and so, consequently, do the phenomena of evaporation, surface tension, and capillarity.” In other words, the wider the bowl, the more volatile aromas are released. In addition, the height of the bowl matters as it determines how close the drinker’s nose is to the wine, and the width of the opening relative to the width of the bowl affects the concentration of volatile compounds. A wide bowl topped by a narrow opening, as in a classic Burgundy glass, would serve to intensify the typically delicate aromas of Pinot Noir, whereas a variety like Cabernet Sauvignon, with its more assertive bouquet, seems to perform better with a wider opening.
In an interesting addendum, Dr. Bartoshuk’s research indicates that, while the smell doesn’t affect a food or drink’s chemical composition (sweet, salty, bitter, sour), it can influence the way those tastes are perceived by the brain. For example, a wine with an abundance of fruity esters may seem to taste sweeter than it actually is. Once again, scientific evidence seems to highlight the primacy of smell over taste as pertains to wine flavor.
Dr. Goode believes that wine professionals process sensory inputs differently than a casual consumer. “Normally, when people smell and taste, it results in one seamless sensation of flavor. But what we do as professionals is different; we try to deconstruct a wine into its elements. And when we do that, we might be changing our own perception as well, in interesting ways.” He goes on to comment, “And because the perception of flavor is created in the brain, you can’t take psychology out of the equation.”
Psychology seems to play an especially important role when it comes to the physical properties of a drinking vessel—how heavy, light, thick, or thin the glass. Even the scientifically rigorous Émile Peynaud believed that the thickness of glass only matters in terms of psychological conditioning. “The rim of a glass (the edge in contact with one’s lips) should be thin, something only possible with crystal. The feeling of thickness does actually influence our impression of what we drink, and we have developed certain preferences in this respect. We prefer beer in a heavy tankard, and while an earthenware mug is all right for a long morning coffee, fine porcelain is preferred for a mocha or an espresso. Ask a taster to try the same wine in two different glasses, one light and fine, the other thick and heavy, and there’s a fair chance he will prefer the wine in the first glass.”
If a wine glass isn’t designed by plotting its course on the map of the tongue, how is it made? According to Maximilian Riedel, entirely by trial and error.
“There is no magic scientific answer,” says Riedel. “And anyway, it’s not us who develop the shape. We work with the trade to develop the glass.” He continues, “Look, we don’t know everything about wine. There are hundreds of grape varieties that we haven’t tasted. So we need to work with the locals and experts to know what they want to enhance.” Their development team typically includes both sommeliers and winemakers, and the process can take a considerable amount of time. “The shape of the bowl, the size, the rim diameter—we have noticed that if you change any of this by even a millimeter, it completely changes the impact. So it is a detailed labor with a lot of fine-tuning.”
Sophienwald goes through a similar process when developing a new piece of glassware, even using 3D-printing to audition the glass prior to production. The possible exception is Zalto, which bases the shape of its bowls on the tilt angles of the earth. But even then, the company has no formula for determining the ideal width of a Bordeaux bowl, for example. The general approach to glass development across all companies seems to be guesswork, informed by the industry, and arrived at by controlled accident.
A wooden mold for a Sophienwald glass. Most hand-blown glasses use wooden molds, while metal molds are more typical with automation (Photo credit: www.ThePerfect.Glass)
Nonetheless, the results are profound. Riedel admits that glass shape is capable of emphasizing one element of a wine over another but says, “I can’t bring out something that does not already exist. I’m not in charge of miracles.” By contrast, the Zalto glasses, per Aldo Sohm, all seem to emphasize earth over fruit. “What I’ve learned is that Zalto is a magnifying glass,” Sohm admits. “If there is even a slight cork taint, you will know. Same with Brett. Some people say they like barnyard. Well, with Zalto, you are on the horse.”
Of course, to the wine professional, the fallibility of a varietally specific design becomes quickly apparent. Says Daniel Johnnes, “It’s not just about matching the variety to the glass; it’s the condition of the wine that matters. For example, take the Syrah glass. I don’t think it’s the same expression with a young Syrah as it is for an old Syrah. For a younger wine, I might want a broader based bowl, to get more oxygen. With an older wine, I might want a smaller glass.”
Indeed, the ability to mix and match is one of the most exciting things about the overwhelming variety of wine glasses on the market. In my own home, for example, I tend to drink Champagne from the Riedel Riesling glass and Burgundy from the Zalto Bordeaux glass, and to decant into whatever is easiest to clean. Riedel may spend untold sums customizing glassware for the industry, but in my house, I customize the glassware selection to my own preferences and limitations.
And then there’s the matching of glass to occasion, perhaps the most important pairing of all. “If I’m having a big party and I’m opening nice wine, but not the most precious bottles from my cellar, then I’m using a basic red wine glass,” says Johnnes, “because people aren’t paying attention.” He continues, “But if it’s New Year’s Eve, I’m going to open some fantastic wine, and I’m going to use some great hand-blown glasses. Similarly, for the restaurants, it’s a part of the overall ambience—as important as the dishes, the silverware, the lighting.”
Having said that, Johnnes also believes that glassware should ultimately be a “behind-the-scenes” concern, never taking center stage. On that point, we completely agree. If I’m too aware of the glass I’m using, it’s usually because it is overly ornate or feels too fragile. On such occasions, as I struggle to swirl the salad bowl-sized balloon or place it back on my table without snapping the stem, I begin to feel ridiculous, too aware of my own airs. In my mind, I’m like a guest at the last great feast before the fall of Rome. I keep casting about for Visigoths in the coat check.
In our pursuit of the perfect vessel for every wine, have we abandoned the refreshing simplicity of the 1950s rebirth that set us on this path? Have we returned to the Victorian aesthetic of decadence for decadence’s sake, only with ornamentation swapped out for terroir elaboration? As a wine professional with a healthy collection of glassware, I have a hard time saying. All the glasses I own feel essential to me. But I can tell you that, on my recent visit to DRC, the Romanée-Conti that was drawn forth from barrel was presented in a basic AP glass. And it tasted magnificent.
Special thanks to Dr. James Shackelford, whose in-depth book The Glass of Wine elaborates on many of the subjects discussed in this article. Additional thanks to Ginger Turner and Morgan Buckley for their kind patience in answering my questions and assistance in image acquisition.
Adams, Paul. “Examining the Science Behind Wineglass Shapes.” SevenFifty Daily, October 8, 2018. https://daily.sevenfifty.com/examining-the-science-of-wineglass-shapes/.
Bartoshuk, L. M. “Taste.” In Sensation & Perception, edited by J. M. Wolfe, K. R. Kluender, and D. M. Levi, 508–537. 5th ed. Sunderland, MA: Oxford University Press, 2018.
Goode, Jamie. I Taste Red, The Science of Tasting Wine. Berkeley: University of California Press, 2016.
Goode, Jamie. The Science of Wine, from Vine to Glass. 2nd ed. Berkeley: University of California Press, 2014.
Peynaud, Émile. The Taste of Wine: The Art and Science of Wine Appreciation. San Francisco: The Wine Appreciation Guild, 1987.
Schoonmaker, Frank. Frank Schoonmaker’s Encyclopedia of Wine. New York City: Hastings House, 1978.
Shackelford, James F. and Penelope L. Shackelford. The Glass of Wine: The Science, Technology, and Art of Glassware for Transporting and Enjoying Wine. Hoboken, NJ: John Wiley & Sons, 2018.
Shackelford, James F. Introduction to Materials Science for Engineers. 8th ed. London: Pearson, 2014.
Zerwick, Chloe. A Short History of Glass. New York City: H. N. Abrams Publishers, 1980.
Without access to the study, I cannot say beyond what the photo conveys. Yes, takeaway is that HIGHER alcohols hug the side of the glass and there's a lower concentration of alcohol in the center.
Check out the video of the vapors - www.youtube.com/watch
Oops. very late in responding here. Basically the higher alcohols like the isoamyls and isobutyl are harsh and volatilize in a ring-shaped pattern around the perimeter of the glass.
To avoid them you would nose in the center of the glass. If you nose a high alcohol wine by moving from the center of the glass to the rim you can even detect those higher alcohols. Mitsubayashi’s team analysed different wines, in different glasses – including different shaped wine glasses, a martini glass and a straight glass – at different temperatures. Here's picture of the glass they used but The study is behind a paywall now - https://pubs.rsc.org/en/Content/ArticleLanding/2015/AN/c4an02390k#!divAbstract so I can't tell you more. It's not an ISO glass.
The study got lots of play when it was first published in Chemistry World.
That is very kind of you to say!
You are a joy to read! You make the medicine easy to take which is something we all must do at the table nightly; inform as needed and delight as desired