What is a Coffee Powder Bed, and How to Raise the Powder Bed in Pour-Over Coffee: Causes of Under-Extraction

FrontStreet Coffee's articles often mention the term "lifting the coffee bed," and many readers wonder how to lift the coffee bed and why it's necessary.

Why Lift the Coffee Bed?

In the final stages of coffee brewing, you might encounter a situation where coffee grounds accumulate heavily in the center of the filter cup, sinking to the bottom and causing "waterlogging." Coffee brewed under these conditions often lacks bright floral and fruit aromas, tasting flat and hollow—neither sour nor bitter.

To improve this end-stage blockage, besides adjusting the coffee particle size (such as coarsening the grind or removing some fine particles), we can also use water flow to lift the coffee bed. This allows the coffee grounds to distribute evenly and thinly along the filter cup walls, which facilitates better water flow in the later stages.

From the perspective of pour-over coffee principles, the goal is to allow coffee flavors to be extracted more fully and evenly. In other words, how we use water flow to shape the coffee bed into a form that's more conducive to flavor extraction is what we need to achieve. In the initial stages of brewing, attempting to distribute the coffee grounds evenly along the filter cup—preventing them from accumulating at the bottom and blocking it—is the safest approach for beginners.

How to Lift the Coffee Bed and How It Changes Extraction

When we encounter the aforementioned situation, we can modify our brewing technique. In terms of specific operations, the most critical moment comes shortly after the bloom. Because the water and time during the bloom stage aim to wet all the grounds at a 1:2 ratio, during this period, only a small amount of coffee liquid drips into the server below. The water poured after the bloom, on one hand, marks the beginning of pour-over extraction, and on the other hand, transforms the post-bloom "hamburger" of grounds into the U-shaped bowl we want—"evenly distributed along the filter cup edges."

The key lies in using water flow with penetrating power for brewing (such as high-position, center-poured fine streams). At this moment, the bottom filter cannot keep up with the pouring speed, causing the water level to rise instantly. The impact force of the water causes the coffee grounds to tumble, pushing the grounds from the center outward, or rather, spreading them open, naturally forming the bowl shape.

As the U-shaped bowl gradually forms, pouring water from the center toward the circular edges can make the hollow center larger, while the contact area of the naturally expanding coffee bed also slowly increases.

And this "bowl" formed by coffee grounds continuously holds the fresh water we pour in. Regardless of the pouring direction, the water will always pass through the spread-out coffee layer, avoiding the situation where water escapes through the V60's drainage channels due to blockage from accumulated grounds at the bottom. This naturally leads to more complete extraction. This is what we commonly call "lifting the coffee bed."

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