How to Distribute Espresso Coffee Grounds Correctly? How to Use a Coffee Distributor? How Much Pressure is Needed for Tamping Espresso? Coffee Distribution Techniques Shared!

The Art and Science of Espresso Tamping

In espresso preparation, to achieve more stable extraction, we use distribution and tamping techniques to make coffee grounds more evenly distributed in the portafilter. This helps reduce channeling and minimize uneven extraction.

Although these are just two simple actions, there's considerable knowledge behind them. Especially regarding tamping: questions like "How much pressure should be applied?" and "What is the correct way to tamp?" have always been popular topics among beginners. Therefore, FrontStreet Coffee would like to share with everyone today exactly how much force we need when tamping coffee grounds, and how to perform proper tamping.

How Much Pressure Should Be Applied When Tamping Coffee Grounds?

The reason we need to tamp is to compress loose coffee grounds in the portafilter through pressure, making them more compact so that hot water can penetrate evenly for relatively uniform extraction. The reason many people question tamping pressure is primarily because they believe tamping force affects extraction time—greater force leads to longer extraction time.

Because when tamping pressure increases, coffee grounds become more compact. When coffee grounds become more compact, water channels decrease, and with fewer water channels, hot water takes longer to pass through the coffee puck. But is this actually true?

Apparently not entirely. While tamping does affect the density of coffee grounds, this impact is actually much smaller than most people imagine. Let me share an experiment FrontStreet Coffee conducted previously. FrontStreet Coffee extracted three shots of espresso, each using the same dose and yielding the same liquid volume—20g of grounds to extract 40ml of coffee liquid. The only difference was the tamping pressure used: one was not tamped at all, one used 2kg/approximately 20N of force, and the third used 15kg/approximately 147N of force.

Despite the significant differences in force among the three groups, the extraction times were nearly identical: 29s, 30s, and 30s respectively. As for extraction yield and flavor, needless to say, except for the untamped shot which showed slight differences, the other two performed quite consistently. So why does this happen? The reason is actually quite simple! During extraction, the espresso machine applies about 9 bar of pressure to the coffee puck—that's 9 atmospheres of pressure. The force from 9 atmospheres applied to a 58mm diameter puck creates approximately 2380N of pressure, which converts to about 242kg. In the face of 242kg of force, whether it's 2kg or 15kg becomes insignificant.

Furthermore, there's another factor worth noting. According to research FrontStreet Coffee found, La Marzocco specifically conducted tamping force experiments when designing the Swift grinder with automatic tamping. The tested forces ranged from 2 to 30 pounds. They discovered that regardless of the force used for tamping, the bottom of the coffee puck received almost no force. A blogger previously gave an excellent example, comparing it to car crash tests—where the compression and deformation of the car body itself are results of energy absorption.

Therefore, as long as the force we use ensures the coffee puck is compacted, there's no need to be overly concerned. FrontStreet Coffee recommends focusing more on how to tamp the coffee puck evenly—that is, how to achieve proper tamping.

How to Achieve Proper Tamping?

Technically speaking, the "proper tamping" mentioned by FrontStreet Coffee doesn't refer to a specific correct action, but rather to tamping the coffee evenly. As long as you can tamp the coffee grounds in the portafilter evenly, it doesn't really matter what technique you use. This is because although hot water from the espresso machine's group head drips vertically downward, when penetrating the coffee puck, this water seeks paths of least resistance. If the coffee puck isn't level, it can easily cause uneven extraction and channeling.

Of course, tamping without distribution is not advisable! If you only tamp without distributing first, even if you manage to create a level coffee puck, different areas will have uneven density, still prone to channeling. Therefore, we need to distribute the grounds first, then tamp. If you're a beginner who doesn't know how to distribute and tamp evenly, you might want to reference the technique FrontStreet Coffee shares below—it might provide some help.

When not using a dosing funnel, the coffee grounds we dispense into the portafilter are typically concentrated in certain areas, with very little coffee in other spots. In such cases, we cannot distribute directly, because using a distribution tool applies some pressure, causing some compaction. The correct approach is to first gently stir the coffee grounds with your fingers, moving excess grounds to areas where coffee is scarce.

Then gently tap the side of the portafilter to let the coffee grounds settle into their proper "positions."

Finally, use a distribution tool to distribute! This completes the distribution step.

Next, we need to take out the tamper for tamping. As FrontStreet Coffee mentioned earlier, as long as you apply force evenly, you can use any distribution posture or grip. However, if you're not yet able to do this, you can replicate the tamping technique FrontStreet Coffee demonstrates below—this is also the most commonly used tamping method: First, place the tamper into the portafilter, then grip the handle with your middle, ring, and little fingers, while placing your index finger and thumb on opposite edges of the tamper. During tamping, the index finger and thumb need to touch both the portafilter and tamper simultaneously, as this ensures even force application. Then concentrate force on the index finger and thumb and press down. OK, this completes the tamping step.

Since most portafilters have a measurement line, after tamping, you can observe the distance between the coffee puck and the measurement line to see if the distance is consistent across all areas. If it is, congratulations—you've achieved proper tamping. If not, we need to recall the details of our tamping and the angle of the tilted puck to see what needs improvement to achieve even tamping.

- END -

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473