The combination of espresso and milk has always been a source of creativity in Italian coffee, and Dirty coffee is one of the most popular examples. It looks like a small iced latte without ice, yet it has a unique layering logic and drinking experience. Starting from Front Street Coffee's preparation parameters, this article traces Dirty's popularity trajectory in China, traces its origins to Bear Pond Espresso in Tokyo, Japan, and explains why it has become a internet-famous product—from the beauty of its visual dynamics to the layered changes from hot to icy and from bitter to sweet across three sips, while also clarifying its core differences from latte and flat white in terms of cup size, temperature, and drinking method.

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The creative space of espresso is indeed rich; even just the pairing of espresso and milk can give rise to many popular drinks. Dirty coffee is precisely one type of espresso coffee that is much loved after the collision of espresso and milk. Anyone with even a slight understanding of espresso will realize that Dirty is essentially a small-volume iced latte with the ice removed.

Making Dirty is not complicated. Front Street's production parameters are: take a 200ml frozen glass, pour in 160–170ml cold milk, and if bubbles float on the surface, use a spoon to skim them off. Then place the glass directly under the brew head and extract the espresso. During operation, the glass should be as close as possible to the portafilter outlet to avoid excessive impact force from the flow, which could cause the coffee liquid to mix into the milk too early.

The earliest appearance of this kind of "layered coffee" in China dates back to a café in Beijing in 2014, whose method referenced the approach of a Hong Kong barista; at the time it was still a niche drink. Afterward, with the rise of independent specialty coffee shops in major cities, the method of pouring milk first and then adding espresso gradually spread among baristas and gave rise to Chinese names such as "Amber," "Dirty," "White Night," and "Dirty Coffee."

Tracing it to its source, the originator of Dirty is Katsuyuki Tanaka of Japan. In 2009, he opened Bear Pond Espresso in Kitazawa, Tokyo, and Dirty has been a signature product since opening, written on the menu as B.P Dirty. The most special thing about Katsuyuki Tanaka's B.P Dirty is that it is paired with his original espresso, "Angle Stain." He deliberately chose to extract with a bottomless portafilter, judging the extraction state by visual observation, and the espresso would leave marks on the cup wall like falling tear streaks.

Relying on dark roasting, a large dose, extremely high concentration, and a relatively low extraction yield, the double "Angel Stain" makes the coffee liquid in B.P Dirty sink slowly, and even without pre-chilling the cup, the layering can be maintained for a relatively long time. However, B.P Dirty did not become widely popular in Japan; instead, it was referenced and learned from by some cafés in Hong Kong and Thailand.

Why is such a small cup of Dirty so sought after? Front Street has roughly summarized the reasons in the following aspects.

First, Dirty itself has the genes of an internet-famous product. It became popular around 2018–2019, when "dirty" foods were becoming trendy internet-famous foods, and dirty buns were especially popular beyond their niche. This kind of food mainly aims to create a "dirty" visual effect. The early definition of "dirty" coffee was not unified, and there were also approaches using milk foam plus cocoa powder to create a "dirty" visual impression. (Internet-famous products change extremely quickly; the later-popular matcha set with "forgiveness green" has now also faded from view.)

Later on, specialty coffee shops spontaneously unified the definition of "dirty" coffee: freshly extracted hot espresso slowly seeps into pure white cold milk, thereby forming a visual "dirty" effect.

Second, it makes up for the lack of visual appeal of iced coffee. To put it bluntly, it looks good. Among hot coffees there are varieties like latte that can be made with latte art, while iced coffee, once placed in a transparent cup, mostly shows only a gradient from golden to brown. The beauty of Dirty is dynamic—the dark coffee liquid slowly descends, gradually staining the white dirty bit by bit. It is very pleasing to the eye and is also a popular subject for photos and check-ins.

Third, the richly layered tasting experience. If Dirty relied only on its appearance, it could not have reached the level of exploding in popularity. The iced lattes served by cafés today can also create layering, but when drinking them people often still tend to stir the milk and coffee together.

What Dirty tastes for is precisely its varied layers. A small cup of Dirty can be finished in three or four sips: the first sip is intense and warm espresso (with a small amount of cold milk), bringing a solid coffee aroma;

the second sip enters the transition zone between coffee and milk, where part of the coffee and milk are not yet fully integrated, allowing you to taste a rich milk chocolate flavor; the third sip is cold milk with a faint lingering coffee aroma. Because there is no ice to dilute it, the overall mouthfeel is quite full, and from bitter to sweet, from hot to icy, the layered experience is very rich.

The above content is compiled by CoffeeHunters, a coffee news website.