Coffee Tamping: The Essential Steps for Proper Espresso Tamping Technique

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Introduction

Espresso is the foundation of Italian coffee, and making espresso can be said to be the core skill that every barista must learn. The process of making espresso is generally divided into grinding coffee beans, distributing coffee grounds into the portafilter, leveling the grounds, tamping, and finally extracting the espresso. These seemingly simple steps are actually full of details, while also requiring accurate measurement of each coffee dosage, espresso extraction amount, and extraction time.

Among these steps, distributing and tamping might be the parts where many baristas need to spend significant time and effort. Today, FrontStreet Coffee will share some insights specifically about the tamping process.

What is the Purpose of Tamping?

Tamping refers to using a tamper to compact the coffee grounds in the portafilter, forming a puck-like shape. So is tamping necessary? And what is the purpose of tamping? FrontStreet Coffee will first demonstrate with a comparative brewing experiment.

FrontStreet Coffee extracted two groups of espresso, with the only difference being whether tamping was applied. One group was tamped as the control group, while the other was not tamped as the experimental group. All other parameters were kept identical. Coffee dosage was 20 grams, extracting 40 grams of espresso liquid.

The normally tamped espresso extracted properly with stable flow, resulting in a final extraction time of 27 seconds. In contrast, the untamped group immediately shot out espresso liquid at the beginning of extraction, with overall faster flow that appeared watery and unstable. The entire extraction time was 8 seconds faster compared to the normal control group, and the taste was also more watery and bland compared to the normal group.

In the process of making espresso, the first step is grinding coffee beans and evenly distributing them into the portafilter. The purpose of distribution is to evenly spread the loose coffee grounds throughout the portafilter. At this point, the coffee grounds are still in a loose state, with varying sizes of gaps between the particles. If extraction were performed directly without tamping at this stage, under the high pressure of 9 bar from the coffee machine, water would flow quickly through the coffee grounds. Because of the loose state, the coffee grounds would be directly dispersed by the water flow, while the water would seek easier paths to pass through. These easily accessible areas would be over-extracted, which is commonly known as channeling.

Therefore, we understand that the purpose of tamping coffee grounds is to compress them, reducing the gaps between coffee particles, providing sufficient resistance against water flow during extraction, and allowing the water to extract the coffee grounds evenly.

How to Tamp Correctly?

Now that we understand the importance of tamping, how should we do it? What aspects should we pay attention to when tamping coffee grounds?

Tamping might seem quite simple, but there are actually many details to pay attention to. Taking FrontStreet Coffee's baristas as an example, when tamping, first ensure the portafilter is level horizontally. Hold the tamper handle with your palm, with the thumb-webbing facing downward, and thumb and index finger gripping the tamper base. When tamping, the elbow joint, forearm, tamper, and portafilter should form a straight line perpendicular to the horizontal. Apply vertical force downward in one motion to compact the coffee grounds.

As we mentioned earlier, the purpose of distribution is to evenly spread coffee grounds in the portafilter because water seeks easy paths during extraction, leading to channeling. Similarly, tamping also requires attention to even compression. Many details of tamping are aimed at more evenly extracting coffee and avoiding channeling caused by unevenness. For this reason, FrontStreet Coffee believes the main aspect to pay attention to is the direction of tamping.

The tamping direction must be perpendicular to the coffee puck. If the tamping direction is tilted, the coffee puck will have an uneven shape, with one side higher than the other. The higher side of the puck will have lower density, while the lower part will have higher density, which can easily lead to uneven water extraction. FrontStreet Coffee recommends two methods for baristas who tend to tilt when tamping: one is to grip the tamper with three fingers, as three fingers can better sense the overall downward direction, reducing errors. The second method is to switch to a calibrated tamper that ensures vertical pressure. With the assistance of proper tools, directional issues can almost be completely resolved.

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