What Causes Coffee Ground Blockage in Pour-Over Brewing? Why Use the Three-Stage Method? What's the Purpose of Flow Restriction?

When you're brewing coffee and notice that hot water isn't draining properly, with significant amounts remaining in the filter even after most of the estimated time has passed, there's no doubt - it's blocked! If you don't cut off the flow in time, your coffee will likely develop some unexpected flavors!

If you want to prevent such "accidents" from happening frequently, you need to identify the problems and correct them promptly after they occur. Based on FrontStreet Coffee's years of experience in troubleshooting coffee brewing, we've identified three main factors that contribute to such occurrences!

1. Fine Powders Blocking the Filter Paper

After brewing, if you notice that the coffee grounds appear muddy, there's no question - it's because there are too many fine powders that have blocked the gaps in the filter paper.

Fine powders are extremely small particles produced during the coffee grinding process! Regardless of the quality of your grinder, some fine powders will inevitably be generated. However, good grinders produce fewer fine powders, while poorer ones produce more (affecting particle uniformity). An appropriate amount of fine powders can add more complexity to your brewed coffee, but when they're excessive, they can easily block the filter paper. That's why people often say that the quality of a grinder can determine the quality of a cup of coffee.

The problem isn't that serious - as long as it's not for commercial use, even a lower-quality grinder is acceptable. We can reduce the impact of fine powders by sifting them out or by using a coarser grind and increasing water temperature. However, it's worth noting that even with reduced fine powders, coffee can still experience blockages. For example, due to the second factor: human influence!

2. Improper Brewing Methods

If at the beginning of brewing, the drainage speed is stable and smooth, but suddenly slows down or even accumulates water in the later stages, then this situation is caused by improper brewing techniques. During the brewing process, if we pour with too much water flow or stir too vigorously, it's easy to carry all the small coffee particles and fine powders to the bottom of the filter cup. These can easily cause blockages in drainage, extending our extraction time.

Therefore, proper water pouring techniques are essential skills for making delicious coffee. Appropriate water flow and proper agitation can increase the margin for error during extraction and reduce the occurrence of blockages.

3. Lighter Roast Levels

Ultimately, light-roasted beans are the main culprits behind brewing blockages. Because when coffee beans are roasted to a lighter degree, their expansion is minimal. This means the bean fibers remain more intact, with relatively higher density. To extract the flavor compounds from the coffee properly and adequately, we need to increase the surface area of coffee grounds in contact with water by using a finer grind. However, this is precisely why light-roasted beans are prone to causing blockages during brewing.

Not to mention the fine powders generated from bean collisions, the high density means coffee grounds are heavier and more likely to sink in water, while the small particle size represents that there will be a higher degree of adhesion between the grounds. When coffee grounds absorb sufficient moisture during brewing, they sink to the bottom. Then, due to the small particle size, they stack more compactly, which directly reduces the gaps for water drainage. Therefore, if you're not careful, brewing light-roasted beans will start to accumulate water.

Therefore, for brewing light-roasted beans, FrontStreet Coffee recommends implementing "coffee bed management." Simply put, during the brewing process, use water flow to wash the coffee grounds accumulated in the center toward the edges of the filter cup, which can reduce the overall thickness of the coffee bed and provide more space for hot water to flow. The specific operation is: after blooming, start with small circles from the center, which can push the coffee grounds to the edges to form a coffee wall, and then avoid this wall when pouring water during the subsequent brewing process!

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Tel:020 38364473