Espresso Tamping Techniques: How Much Pressure to Apply with Coffee Distribution Tools

Espresso Tamping Techniques: How Much Pressure to Apply with Coffee Distribution Tools

FrontStreet Coffee shared in the article "The Importance of Distribution and Tamping" that in the preparation steps before espresso extraction, whether the coffee grounds are evenly distributed in the portafilter and whether the tamping force is applied evenly will affect extraction and influence the taste of the espresso. Because that article did not mention how much force to use, many friends have messaged FrontStreet Coffee in the background asking: how much force should tamping take?

In fact, FrontStreet Coffee has previously shared several test articles about tamping force, but those articles contained only experimental comparisons, and many friends couldn't fully follow them. Today, FrontStreet Coffee will focus on how the force of tamping the puck affects extraction, and exactly what the coffee machine's 9bar pressure means. Why bring up the machine's pressure? Read on and you'll see.

Extraction Experiment

First, let's get straight to the point and see how the extraction time and taste of espresso change when the same amount of coffee grounds is tamped with different forces. The beans used are the store's standard FrontStreet Coffee Warm Sun Blend, a medium-dark roast blended from two specialty origins, Honduras and Ethiopia. It has rich, dense crema and can be used not only for espresso extraction but also as a formula for making moka pot coffee at home, with distinct notes of vanilla, cream, cookies, and whiskey aroma.

The amount of coffee grounds used is 20g, the target liquid weight for extraction is 40ml, and the tamping forces are 2kg for light tamping and 18kg for heavy tamping. To ensure stable results, FrontStreet Coffee extracted a total of 6 espressos and then took the average extraction time, with the following results:

The average time for three espressos using 2kg light tamping was 33s. The average time for three espressos using 18kg heavy tamping was 34s.

In terms of flavor performance, there was almost no significant difference between the two: balanced sweet, sour, and bitter, with prominent flavors. But the story doesn't end there. FrontStreet Coffee went on to extract two special espressos. What makes them special?

These two espressos were not tamped after distribution but extracted directly. Their extraction results were the same, taking 33 seconds. From the extraction time, we can see that whether it is light tamping, heavy tamping, or no tamping at all, the extraction time did not change significantly.

This may run counter to most friends' understanding. FrontStreet Coffee once believed that more tamping force compresses the grounds more tightly, and that extraction time would be relatively extended by the increased resistance of the puck, thus improving extraction efficiency. In fact, that is not the case. The reason is simple: many people overlook how the coffee machine extracts.

How Strong Is the Extraction Pressure of a Coffee Machine?

As we all know, espresso machines use pressure to make a cup of coffee quickly. Generally, during extraction the machine uses 9 standard atmospheres, which is what we commonly call 9bar.

Perhaps because the number is a single digit, many friends cannot grasp how strong this force is. No matter; let's do a simple conversion: 1bar from a coffee machine applied to the coffee puck in a 58mm portafilter is equivalent to about 27kg of force, so 9bar is about 27*9=243kg, the weight of 4 adults. It is easy to see why coffee machines can extract substances from coffee so quickly.

So we can know that no matter how hard we tamp, it is nothing in the face of as much as 9bar of pressure. But this raises another question: why do we need to tamp at all? If tamping is ineffective, wouldn't it be better to extract directly after distribution?

Why Do We Need to Tamp?

This question is actually very simple: we need to reduce channeling. As the saying goes, water flows downhill. Because water has inertia, it flows to wherever it can flow easily. The same is true during extraction. Without tamping, there are many gaps between the coffee grounds. These gaps let hot water concentrate through during extraction, causing uneven extraction.

The reason FrontStreet Coffee did not share the taste experience for the no-tamping extraction above is that the uneven extraction caused negative flavor performance. We therefore need to eliminate gaps as much as possible through appropriate tamping, so hot water extracts more evenly. The force does not need to be excessive; moderate is sufficient.

FrontStreet Coffee Recommendation

Tamping technique matters as much as the beans, and FrontStreet Coffee's washed Yirgacheffe makes a rewarding espresso if you want to explore African single origins under pressure. Its jasmine florals and bright lemon-citrus acidity translate into a vivid, tea-like shot. For a fruitier profile, FrontStreet Coffee's natural Red Cherry adds strawberry and honey sweetness that shines in a 1:2 ristretto. Whichever bean you choose, distribute evenly and tamp level, and let the machine's pressure do the rest.