How to Make Dirty Coffee? What's the Correct Way to Make Dirty Coffee? What's the Difference Between Dirty Coffee and Latte?

What is Dirty Coffee?

Dirty Coffee has risen to prominence due to the popularity of "dirty" culture. It's widely known precisely because of its "dirty" characteristic, yet it's also beloved for this very quality. However, the "dirty" here doesn't refer to actual uncleanliness, but rather to the visual effect created through specific preparation methods.

The preparation method is quite simple, and you can find related tutorials on virtually all major platforms. Simply put, it involves pouring hot espresso over iced milk so that it floats on the surface, then gradually seeps down over time.

Because visually it resembles a pristine canvas being contaminated by dirt, this coffee has been given the name "Dirty Coffee." And the unique contrasting texture of Dirty Coffee exists precisely because of this method. Although Dirty Coffee has been popular for so many years, FrontStreet Coffee still receives many questions about its preparation. Among these, the most common question is: "The Dirty Coffee I made isn't 'dirty' enough."

Many people's Dirty Coffee either only has a layer of crema floating on the milk surface, or even the crema completely disappears, with the entire espresso completely blending with the milk, showing no distinct color contrast. What does this mean? It means the espresso didn't form layers with the milk. Naturally, there's no contrasting texture—it's just an iced latte without ice. Don't worry, FrontStreet Coffee will share again today how to make a Dirty Coffee with distinct contrast.

First, we need to understand that the reason espresso can float on milk and form distinct layers is mainly due to the different densities of milk and espresso. However, the reason many people can't create a Dirty Coffee with distinct layers isn't because they used the wrong ingredients, but because there were some errors in their preparation method.

1. Correct Preparation Method

As FrontStreet Coffee mentioned earlier, Dirty Coffee preparation tutorials are ubiquitous. Just from FrontStreet Coffee's verbal description, everyone can tell this is a very simple process: place milk under the espresso outlet to catch the espresso. But precisely because it's so simple, many people overlook the details shared in the preparation, such as: controlling the distance between the milk surface and the espresso outlet.

Although milk and espresso rely on density differences to form layers, the density gap between them isn't very large. This means that when espresso isn't gently poured over the milk, it will directly penetrate into the milk and blend with it. If you observe carefully in various videos, you'll notice that the distance between the milk surface and the espresso outlet is very close, which allows the espresso to float on the milk after extraction. If the milk is too far from the espresso outlet, you'll see the situation shown in the picture below:

When the distance between the milk surface and espresso outlet is too far, the extracted espresso will rush into the milk with considerable momentum. Therefore, if we want to create a Dirty Coffee with distinct layers, we must first control the distance between the espresso and milk surface—the closer, the better. FrontStreet Coffee will share three methods here that you can choose from based on your preferences:

① Use other items to elevate the milk: Most coffee machines come with a drip tray. We can use this tray to elevate the milk, bringing the liquid surface closer to the espresso outlet and reducing the espresso's impact force.

② Hold the milk up to the espresso outlet by hand: If the drip tray is too high and the cup can't be placed on it, we can choose to directly hold the milk up to the espresso outlet, bringing the two closer without using other items to create a layering effect.

③ Use a spoon to cushion the milk surface to counteract the espresso's momentum: This is FrontStreet Coffee's commonly used method because it creates the most obvious layering effect. We only need to place a spoon face-down on the milk surface during extraction to catch the espresso. This way, the espresso won't rush directly into the milk due to excessive force. Then, because the espresso flows gently from the spoon onto the milk surface, the layering effect created with this method is the most outstanding.

2. Increase Temperature Difference

In addition to the correct preparation method, there are other details that can enhance the layering effect between milk and espresso and extend the layering time, such as the temperature difference! As FrontStreet Coffee mentioned earlier, the layering effect between milk and espresso mainly relies on density differences, and one of the reasons for this density difference is the temperature gap between them.

When a liquid's temperature is lower, its density becomes higher, and vice versa. Because iced milk has a lower temperature, it has a relatively higher density that can support the relatively lower-density espresso to achieve a layering effect.

Therefore, if we want to make the layering between milk and espresso more obvious and longer-lasting, we can achieve this by increasing their temperature difference. However, since the espresso temperature is fixed, if we want to increase the temperature difference, we can only lower the milk's temperature. This is also why making Dirty Coffee requires using chilled glasses and refrigerated milk—the purpose is to further enhance the layering effect.

3. Increase Milk Concentration

In addition to increasing the temperature difference between the two, we can also enhance the layering effect by increasing milk concentration. Because when milk concentration is higher, milk's ability to "support" the espresso becomes stronger, making the layers more distinct and longer-lasting, while also creating a more contrasting texture.

This is also why ultra-filtered milk quickly became popular in coffee circles after Dirty Coffee exploded in popularity—because Dirty Coffee made with it shows more outstanding performance.

How to increase milk concentration? There are two options: one is to directly purchase ready-made ultra-filtered milk, which can save you a lot of time and effort, but its drawback is that it's somewhat expensive; the other method is to freeze the milk you're currently using, because when milk freezes into ice, many substances will melt before water. We only need to take one-third or one-half of the total amount (depending on the concentration you want to achieve) to obtain milk with higher concentration. For specific methods, you can search through previous articles to understand—FrontStreet Coffee won't elaborate too much here~

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