How to Bloom Pour-Over Coffee? How Much Water Should Be Used for Blooming?

Why Use Twice the Coffee Weight for Blooming?

Recently, FrontStreet Coffee has published numerous experimental articles about pour-over coffee. In each brewing guide, FrontStreet Coffee consistently mentions "using twice the coffee weight in water for blooming," and on other platforms, most tutorials recommend this same blooming water amount! This often leads beginners to ask: "Why must we use twice the coffee weight in water? Would using more or less water not work?"

Excellent! FrontStreet Coffee loves friends who ask questions! The desire for knowledge is truly precious (after all, it provides FrontStreet Coffee with article material)! So today, FrontStreet Coffee will share why blooming requires twice the coffee weight in water~

The Purpose of Blooming

Using a small amount of hot water to wet the coffee grounds and waiting for 30 seconds—this action is called "blooming." The main reason blooming is necessary is to force out the carbon dioxide hidden within the coffee grounds with hot water. Otherwise, the carbon dioxide will obstruct the hot water from extracting the aromatic substances from the coffee grounds, affecting the extraction!

How Much Water Should Be Used for Blooming?

Therefore, we need to thoroughly wet all the coffee grounds in the filter at the beginning. But this is an ideal state!

When dry, coffee grounds will absorb some of the hot water to become saturated. If the water amount is too small, this small amount of hot water will be absorbed by the upper layer of coffee grounds, and the coffee grounds accumulated at the bottom of the filter will not have properly released gas during the blooming stage. This leads to uneven extraction during the subsequent brewing process—the upper layer coffee grounds will already be in the middle stage of extraction, while the bottom layer coffee grounds are still in the degassing state.

However, it's important to know that the water absorption capacity of coffee grounds is limited. Therefore, if too much hot water is used for blooming, when the coffee grounds reach saturation and no longer absorb water, this unabsorbed hot water will directly drip into the lower pot. Since the coffee grounds have not yet properly released gas at this point, this portion of hot water that drips into the lower pot has little effect. Moreover, if the amount is excessive, it will also dilute the entire cup of coffee.

The Science Behind Using Twice the Coffee Weight

FrontStreet Coffee mentioned in the article "What are powder-to-water and powder-to-liquid ratios?" that if we brew a pot of coffee with a 1:15 powder-to-water ratio, the final coffee liquid obtained will be 2 units less than the amount of hot water poured in, and this portion is the hot water absorbed by the coffee grounds. Therefore, we can conclude that during the blooming stage, the amount of water that just allows all coffee grounds to be wet is twice their weight, which is also the maximum water storage capacity of coffee grounds.

Why Water Still Penetrates When Using Twice the Weight

But often you'll find that even though you've poured twice the coffee weight in water, a lot of hot water still directly bypasses the coffee grounds and seeps through.

There are many reasons for this! First, because coffee grounds need time to absorb hot water, if you pour all the hot water at once, it's easy for the coffee grounds to not have enough time to absorb before the water runs away! Second, it's related to the quality, density, and size of the coffee grounds. With the same grind, dark roast coffee grounds will have a higher water absorption rate than light roast because dark roast coffee beans have a looser texture, allowing water to be absorbed more quickly and reach saturation. So when you use the same hot water for different roasts, the pot with light roast coffee grounds will have more hot water bypassing the coffee grounds and dripping into the lower pot.

Then there's the grind size—the finer the grind, the smaller the coffee particles, the larger the surface area hot water can contact, and the easier it is for water to penetrate into the interior of the coffee grounds. At the same time, the gaps between particles will also shrink significantly, causing water to take longer to penetrate to the lower pot. The last factor is the freshness of the coffee beans. If the coffee beans have been stored for a long time, the carbon dioxide inside has long been lost. This way, when hot water is poured, it won't create a large dome. The dome can slow down the flow rate of water. When the gas is exhausted and the dome can't form, the hot water will flow down quickly, and at this point, blooming is no longer needed!

Conclusion

So overall, when the beans are fresh, the best blooming plan is to pour twice the coffee weight in water. This won't cause excessive penetration of useless hot water, nor will it cause uneven extraction due to insufficient water.

The pouring method can be from inside to outside and then from outside to inside in circular motions, focusing on the center but wetting the coffee particles around the edges. This allows a small amount of hot water to maximize its effect, enabling the coffee to achieve more even extraction!

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