The Real Science Behind Latte Art [Thoughts After Dark]

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Latte art

Thoughts After Dark answers the questions you have in the final moments before drifting off to sleep when a simple Google search turns into an hour-long exploration into how things are made and how they work. Your random late-night questions are answered here — even the ones you didn’t know you had.

We’ve all seen latte art photos online. The elaborate snowman in the dead of winter, the traditional leaf design, and even a swan if you go to the right coffee house. I love watching patrons in my local café trudge to the front of the shop to grab their prepared latte, spot how aesthetically pleasing the design is, and then carry the cup carefully back to the table; sure not to ruin it before their first sip. 

A few months ago, my boyfriend and I splurged on a nice espresso machine. We knew it would, eventually, save us money, as we used to go down the street to grab a latte a few times a week (which adds up quickly). Since then, I’ve tried my hand at simple leaf and heart designs on my homemade oat latte with very little luck. They usually come out looking more like a blob or circle than anything else. 

Making the perfect latte is an art — especially when you consider the aromatic, caramel-colored crema on the espresso shot, getting the milk frothed at the right temperature to form a foam, and adjusting the ⅔ milk, ⅙ espresso, and ⅙ foam ratio. Beyond that, each component of the machine needs to be warmed up before you can even start pulling your shot. 

So, how does latte art work? And can you master the art of coffee?

What You Need to Know About Latte Art  

While latte art really began in Italy decades ago, it was U.S. coffee shops that popularized it in the late 1980s. Since then, people have become more knowledgeable about what makes a good cup of joe, but the rise of social media and sharing aesthetically pleasing photographs really accelerated the trend.   

Successful latte art really depends on the foam. Foams form by dispersing gas into a liquid or solid. Even small changes to the temperature or airflow can ruin a silky foam. 

"Foams are very complex and interesting fluids," Emilie Dressaire, an engineer who leads the Particles, Interface, and Fluids Lab at New York University told Live Science.

When milk is steamed properly, it actually tastes sweeter and gives the espresso a velvety, thick texture. But to steam the milk, there are a few steps to consider. Using a “steam wand” that pumps steam into a pitcher of milk, the milk is spun around and around to create small bubbles referred to as microfoam. 

The molecules in the steamed milk that don’t interact with water, or the fats, actually create the porous foam. The reason the latte art seems to float on top of the coffee is that the milk foam can “hold other fluids” and remain elastic enough to manipulate it into a design.

To ensure the design turns out the way they want it to, baristas are also careful with how quickly they pour the milk into the cup. Almost every design begins in the middle of the mug, before being pulled into a specific design like a tulip or heart. 

If you’re a non-dairy milk drinker, you’ll likely only get good latte art if it’s made with almond or soy milk, as other dairy alternatives don’t have adequate protein to form a proper foam. 

Keep in mind that latte art doesn’t actually taste like anything. So, although we do all eat with our eyes first, what’s really important is that the coffee is made right. 

Breaking Down Temperature

To get really specific about temperature, the best milk to froth is very cold, refrigerated milk. For lattes specifically, skim, 2%, and whole milk work best. 

Because milk proteins begin to break down and burn at around 170 degrees, steaming milk to about 155 degrees is the sweet spot, while 160 degrees is preferred when taking the beverage to-go. 

While the fat in whole milk may weigh down the foam and make coffee art more difficult, it does produce the richest tasting cappuccino. 

Becoming a Starbucks Coffee Master

What if instead of being a mixologist, someone wants to be a master barista and work with coffee instead of alcohol? Like most professions, mastering your craft comes with a deep understanding of its history and working your way to the top. 

If you visit a Starbucks and see an employee in a black apron, this means they’ve earned the title of coffee master. Before a barista can become certified, they have to complete a coffee passport within one year, as well as exhibit a good attitude and communication skills at work. 

Once the Starbucks Coffee Master certification begins, the barista begins to gather an even deeper understanding of coffee. Using their work-provided coffee passport, they make their way through a variety of flavor profiles and roasts.  

When they complete the passport, the employee is then tested by comparing at least two coffees and answering a number of questions about the brew, roast methods, and the history of Starbucks. These questions may include: 

  • What is the general taste profile for the 3 main growing regions?

  • How does coffee processing affect flavor?

  • What are Starbucks' ethical-sourcing guidelines?

With an ongoing commitment to coffee education, a Starbucks black apron barista probably knows the answer to your latte-related question — so keep an eye out next time you stop in for a cup of java. 

And, if you spot a purple apron, you’ve just been served a coffee by a barista champion who has won a Starbucks coffee competition. 

Read more from Thoughts After Dark: 

Image Credit: amenic181 /

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