Pour-over Coffee Blooming Technique: Proper Method, Water Amount, and Timing - Yirgacheffe Brewing Parameters

Regarding blooming issues, FrontStreet Coffee has covered quite a bit about water pouring techniques, coffee bed expansion, and how blooming water amount and time affect flavor. These are all observations made from above the filter cone. This time, let's observe the issue from below the filter cone.

First, let's repeat the basics: the blooming step is primarily designed to release gases from the coffee grounds. It's also known that coffee grounds absorb twice their weight in water. Therefore, for beginners, controlling the blooming water amount to twice the coffee weight is a reliable approach.

However, careful observers will notice that when blooming with twice the amount of water, quite a bit of coffee liquid flows into the server. This means the coffee grounds haven't completely absorbed the water.

This situation is actually normal. Hand-drip coffee typically uses a grind size similar to sugar granules. While it may appear that all coffee grounds have been moistened, in reality, only the surface of the coffee particles gets wetted, while the interior of some coffee grounds remains unpenetrated by water. This causes excess water (coffee liquid) to flow down.

The amount of coffee liquid flowing into the server is related to the following factors:

1. Coffee Grind Size

When ground finer, water doesn't easily penetrate downward, staying in the coffee bed longer, but if too fine, it will cause water pooling. If coarser, the coffee grounds expand better, but correspondingly, the gaps between coffee grounds become larger, allowing water to flow away more easily. When the gaps are too large, the coffee bed can easily collapse.

Therefore, you can also reverse-engineer this: when blooming with twice the water amount, if water drips into the server very slowly, it indicates the coffee is ground too fine. If water drips very quickly with more water in the server and collapse in the middle, then the grind is too coarse.

2. Coffee Roast Level

Under equal conditions, dark roasted coffee absorbs water more easily, thus less water flows into the server. Light roasted coffee absorbs water more slowly, so relatively more water flows into the server. Generally speaking, with 15g of coffee grounds and 30ml of blooming water, dark roast yields about 3-6ml of coffee liquid, while light roast yields about 5-10ml.

3. Pouring Technique

Regarding blooming water pouring, you can refer to the article "How to Pour Water Reliably for Blooming" for details. If you pour more around the outer edge, it will cause some water to flow away from the sides. For some light roasted coffees with less obvious expansion effects, pouring in small circles around the center might leave the surrounding coffee grounds unmoistened. This will also cause more water to drip into the server.

If you accidentally pour too much water, it will also cause excessive dripping during blooming. For example, if you planned to pour 30ml but actually poured 35ml.

Aside from the issues mentioned above that need attention, it's normal for a small amount of coffee liquid to drip when blooming with twice the water amount, and it won't significantly affect subsequent extraction. Of course, some experienced friends might choose to use less water for blooming to avoid excessive coffee liquid dripping into the server prematurely. However, FrontStreet Coffee doesn't recommend this approach for beginners, because without full proficiency, using less than twice the water amount makes it difficult to completely moisten the surface layer of coffee grounds. Therefore, sticking to twice the water amount for blooming is more reliable.

FrontStreet Coffee's blooming phenomenon when making coffee is that dripping starts just as the blooming water pour is about to end (around the 7th second), with coffee liquid dripping into the server in droplets (sometimes the first second might be a thin stream), then stopping dripping between the 15-18th second. You can use this as reference (not necessarily following this standard). If you think too much coffee liquid is dripping into the server during blooming, you can find the cause from the three points above.

Important Notice :

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