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Your first espresso brew log probably looked something like this.

Your first espresso brew log probably looked something like this.

1. Channeling

Some “V”-shaped curves are likely caused by channeling.

Some “V”-shaped curves are likely caused by channeling.

Compared to distinct “V” shapes appearing in the later phase, those observed early in extraction — which likely indicate channeling — were more often associated with unpleasant taste profiles.

Compared to distinct “V” shapes appearing in the later phase, those observed early in extraction — which likely indicate channeling — were more often associated with unpleasant taste profiles.

When channeling happens several times in a row, the V shapes sometimes overlap and look wavy or uneven. In those cases, the taste was sometimes worse than when there was just one clear, big channeling event.

When channeling happens several times in a row, the V shapes sometimes overlap and look wavy or uneven. In those cases, the taste was sometimes worse than when there was just one clear, big channeling event.

2. Initial EC

It has been observed that the initial EC curve—whether sharp and high or gentle and low—can significantly affect extraction patterns and flavor profiles.

It has been observed that the initial EC curve—whether sharp and high or gentle and low—can significantly affect extraction patterns and flavor profiles.

• Before stream formation under the basket, when drops fall from several spots, the EC sometimes appears flat or gently decreases. • When the early EC stayed flat for too long, the shots were usually less repeatable.

• Before stream formation under the basket, when drops fall from several spots, the EC sometimes appears flat or gently decreases. • When the early EC stayed flat for too long, the shots were usually less repeatable.

3. Various Shapes

• Left: When puck resistance was extremely low, the log often looked like the one on the left. For example, coarsely grinding very old beans and under-dosing often produced this shape. These shots were highly repeatable, but the flavor was often unsatisfying. • Right: As puck resistance increased, the log started to show step-shaped curves like the one on the right. The higher the resistance, the more signs of channeling appeared, and repeatability dropped. • Balance point: Some users found a balance point where both flavor and repeatability were excellent. They used their best-tasting log as a reference and added proper tools to the dialing process to stabilize results.

• Left: When puck resistance was extremely low, the log often looked like the one on the left. For example, coarsely grinding very old beans and under-dosing often produced this shape. These shots were highly repeatable, but the flavor was often unsatisfying. • Right: As puck resistance increased, the log started to show step-shaped curves like the one on the right. The higher the resistance, the more signs of channeling appeared, and repeatability dropped. • Balance point: Some users found a balance point where both flavor and repeatability were excellent. They used their best-tasting log as a reference and added proper tools to the dialing process to stabilize results.

✓ Scenario

Let’s imagine this: The dashed line is the previous brew and serves as the reference. The solid line is the next brew, which I’m analyzing now.

Let’s imagine this: The dashed line is the previous brew and serves as the reference. The solid line is the next brew, which I’m analyzing now.

  1. “In the new log, the initial EC was lower. During that time, coffee dripped slowly, drop by drop. This was expected since the puck resistance had increased. However, the slow-dripping phase should not last too long.”
  2. “Once the stream formed, the EC dropped quickly. A small V-shaped dip appeared in the middle, likely caused by channeling. Still, the taste was excellent, so I decided not to treat it as an issue.”