If you’ve been around beer nerds for any period of time, you’ve likely heard the term “nucleation point” thrown around, but what does it actually mean, and how does it impact your drinking experience? To give us a starting point, let’s look at Encyclopedia Britannica’s definition of nucleation:
“nucleation, the initial process that occurs in the formation of a crystal from a solution, a liquid, or a vapour, in which a small number of ions, atoms, or molecules become arranged in a pattern characteristic of a crystalline solid, forming a site upon which additional particles are deposited as the crystal grows.”
Encyclopedia Britannica
To bring that definition to the context of beer, a nucleation point is a glass defect, piece of residue, or intentional etching that acts as a starting point for CO2 breaking out of solution. Often times you’ll notice tiny streams of bubbles in a glass of beer – those streams are originating at nucleation points.
What’s odd is that nucleation points can be both good and bad, so let’s start by looking at a situation in which they’re a welcome sight:
When nucleation points are helpful
As discussed in my post about shaker pints, head (beer foam) formation and retention are vital to the drinking experience. Beer foam carries desirable aromatics and is aesthetically/texturally pleasing to the drinker. Because of this, and because not all beer produces consistent, frothy head, some establishments use nucleated glasses – glassware that has been laser-etched at the base. The etching acts as nucleation points for CO2 to break out of solution and more rapidly resupply the fading foam.
In general, this is positive for styles that rely heavily on aroma (think Hazy IPAs), but it can also be beneficial to everything from a German Pilsner to an American Stout since aroma is influential in every style of beer.
Given that purposeful nucleation can be so useful, in what circumstances are nucleation points undesirable?
When nucleation points should be avoided
Drinking slowly
Although etched glassware can be fantastic for a variety of styles, it’s not ideal if you’re planning to drink slowly. By nature of a nucleation point, CO2 is breaking out of solution faster than it would be naturally. As such, you may end up with a flat beer if you’re nursing a 10% ABV Imperial Stout in a nucleated glass.
The time frame you’ll have will vary by beer (not all beer is carbonated to the same level) and environment (temperature greatly influences how fast CO2 leaves solution), so a good rule of thumb is to avoid nucleated glassware when drinking high ABV styles (Imperial Stouts, Barleywines, etc.) that will likely be consumed more slowly.
Dirty glassware
The other case where nucleation points are unwanted is when they result from improperly cleaned glassware. When I shared three reasons to send your beer back, one was due to glassware that isn’t beer clean. The Brewers Association describes it well in their Draught Beer Quality Manual:
“A perfectly poured beer requires a properly cleaned glass. As a starting point, glassware must be free of visible soil and marks. A beer-clean glass is also free of foam-killing residues and lingering aromatics such as sanitizer.”
Draught Beer Quality Manual
When a glass isn’t beer clean, the remaining residue becomes nucleation points – it’s pretty gross. Even if* those points lead to a more robust head, is it worth drinking out of a dirty glass?
*Ironically, even though a dirty glass creates a host of nucleation points, the grease, detergent, and other suspect residues can actually hurt head retention.
Final thoughts
Next time you’re imbibing and spot streams of bubbles rising to the surface of your beer, consider what they’re caused by and whether it should prompt any action. Maybe you’ll realize the glass is nucleated and judge the beer less fiercely for not “maintaining its carb”. Maybe you’ll realize the glass is dirty and kindly ask for another. Maybe you’ll see it as an opportunity to impress your friends with some interesting beer knowledge.
Whatever the case, enjoy the beautiful beverage you’re about to consume. Cheers!