Sensory perception is such an intangible thing. There are so many variables at play in evaluating a spirit, from the emotional and environmental factors to our own inherent biases, that it is a wonder that there is any kind of consensus at all. How do we take what is a very personal translation of a spirit and successfully portray it as something that is meaningful and measurable to others?

There are many institutions and methodologies in sensory evaluation and most tend to adhere to the same fundamental principles of assessing the appearance, aroma and taste of a spirit. Clarity and condition are considered; intensity, length and complexity are scrutinized and a broad vocabulary of commonly used terms is employed to describe the vast array of aromas and flavors that cross our senses. We strive to minimize the distractions of the world around us, eliminating extraneous factors, and we endeavor to deliver an honest, impartial assessment of the liquid before us. We spend inordinate amounts of time, energy and money improving technique and honing our skills, but how much attention do we pay to the glass itself, and how much impact, if any, does it have on our determinations? Does the shape of the glass have an impact on our perceptions of aroma and flavor?

In times past, things were simple. There was a copita for the serious analyst, a snifter for the connoisseur and the rest of us made do with a rocks glass. Times have changed, and the last decade or so has seen an outpouring of glassware to maximize the enjoyment of a spirit and enhance its organoleptic, or sensory, attributes. Some are more aesthetically pleasing, designed for style over performance. Others claim to be ergonomically and scientifically designed to bring out the best of what is in the glass.

The array of glassware available is overwhelming. It seems that every spirit category now has its own specially designed glass. Herein lies part of the problem. Each of us has our own idea of what the perfect glass is. Our own partiality to a particular idea of form and function can sway our opinion before we even pick up the glass. If the shape of the glass is too far removed from our preconceived notions of what is correct, then we are already stacking the deck unfairly, regardless of the merits of the glass. Likewise, if the glass doesn’t feel right in our hand or the glass is too thick, it can be difficult to get beyond this and give the spirit a fair assessment.

Once someone has decided what they think is the best glass, it is very difficult to change that opinion. As much as we like to believe that these decisions are impartial, we generally pick a glass based on recommendation or endorsement and rarely have the time or inclination to compare various glasses side by side. Liquor companies and glass manufacturers have slick marketing machines and lots of shiny bells and whistles to coerce and cajole us into believing that their glass is best.

When teaching classes, I tend to use an ISO glass when available. International Standards Organization, or ISO, glasses are recognized internationally as the standard design for tasting. The rounded bowl and narrow sides allow a wine or spirit to be swirled easily without any spillage. The rim helps contain all the delightful aromas and enhances the appreciation. These glasses are designed to be used across a broad range of alcoholic beverages and styles when the objective is to taste spirits comparatively. ISO glasses are used when it is more important to be as consistent as possible with as many of the variables as possible in order to evaluate each sample fairly.

In recent years, the general consensus of the industry seems to be that the most effective glass to use for spirit tasting has a basic tulip-like design. These glasses vary in looks but all tend to share several commonalities: a relatively wide bowl for easy swirling and maximum evaporation, and a convergent rim to capture as many of the aroma compounds as possible. As most of what we consider to be flavor is actually aroma, rather than taste or texture, it makes sense that so many of the glasses available focus on increasing our perception of volatile aroma compounds.

A wide bowl means lots of surface area, which helps to maximize evaporation. If the glass is too narrow, then all that we are likely to be smelling is ethanol, as it tends to be more volatile than some of the heavier congeners. The height of the glass also plays a key role here. Some glasses are simply too shallow and do not provide enough headspace (the space between the surface of the liquid and the rim) for the aromas to develop before we bring the glass to our nose.


In terms of the preferred type of rim, there seem to be two schools of thought: those who want to capture as many of the aroma compounds as possible, and those who want to be able to lessen the impact of ethanol on the nose. If you choose to dilute your spirit (I generally dilute to around 60 proof), then the convergent rim stands out as a great way to maximize your ability to perceive a fuller range of aromas, particularly in a high-congener spirit or one that has a lot of botanicals present. However, with the prevalence of high-proof and cask-strength offerings in the last few years, having a glass with a flared or divergent rim is certainly going to help lessen the risk of overwhelming or anaesthetizing the olfactory bulb with a big hit of ethanol. In fact, there are those who would argue that due to the higher alcoholic strength of spirits, when compared with beer or wine, there is little point in smelling orthonasally (with our nose) at all, but instead we should focus on assessing the spirit retronasally by putting it in our mouth and allowing the higher temperature, together with the drawing in of a little air, to release the compounds that can then be assessed via the back of our mouth, up through our soft palate as we breathe out.

While many glasses focus on maximizing olfaction, several others focus more on liquid dynamics and how the spirit flows from the glass over the tongue. Unfortunately, a lot of the logic here is based on the outdated idea of the tongue map or taste map, whereby we are sensitive to sweetness on the tip of our tongue, bitterness at the back of our tongue and acidity along the sides and thus, to get a full appreciation of the flavors, it is necessary to have a wider flow of liquid from the glass and therefore a flared rim is far more effective. A convergent rim would simply deliver a narrow beam of liquid to a very localized part of the tongue, and therefore you would be getting a one-dimensional profile. The idea of “one tongue map fits all” has long been disproved. Everyone’s palate is different, some of us with more or fewer papillae that make up our taste buds and some of us more or less sensitive to various textural stimuli (fats, oils, tannins, etc.). Perception of flavor is individual, as is where on our tongue and throughout our palate we are most sensitive to bitterness, acidity and sweetness (although we can detect all basic tastes to some degree throughout our tongue).

To compound things further, our sensitivities can change over time, especially as we become more familiar with and tolerant to various spirits. Therefore, there is still a good deal of merit to the idea of getting as broad a flow of liquid onto the palate as possible to ensure that we get the full spectrum of flavors, and to this end a glass with a divergent rim seems the most likely to be able to achieve this. However, the same results could likely be accomplished by simply swirling the liquid in our mouth.

The biggest flaw with the idea of a perfect glass is that we are all imperfect. Our perceptions of aroma and flavor are as distinct from one another as our preferred tipple. What one person may find enjoyable, another may find unbearable. Personal preference will always surpass anything that a glass may be able to hide or enhance. While the shape, size and design of the vessel can all certainly impact how a spirit is initially perceived, it will ultimately be our own notions of the good, bad and indifferent that will dictate our appreciation of or ambivalence toward any particular dram.

Now where did I leave that rocks glass?

Click Here for a chart: The Systematic Approach to Tasting Spirits® Level 2, reproduced by permission of the Wine and Spirit Education Trust.