How to Brew Volcano Pour-Over Coffee from Japanese Three Major Schools? What are the Famous Japanese Brewing Methods? How to Brew Volcano Drip Method?

What is the Volcanic Brew Method?

FrontStreet Coffee has shared this brewing method no fewer than three times, and for good reason. It is genuinely different from traditional techniques. Not only does it draw abundant sweetness out of dark roast coffee, but the whole brewing process is visually spectacular.

Before, FrontStreet Coffee only shared how to use the method. Today, FrontStreet Coffee will break down the principles behind it. Barely worth mentioning, this is a classic Japanese technique known as the "Volcanic Brew Method."

It is called the Volcanic Brew because during brewing, the coffee bed keeps producing scenes that look like volcanic eruptions. That is where the name comes from. The technique creates those eruptions because during extraction it never uses a large flow of water. Instead, it works with small amounts throughout, pouring a little water at a time across multiple intervals.

The Science Behind the Volcanic Effect

As everyone knows, coffee grounds in the filter expand after blooming because they keep releasing carbon dioxide. Because water links the coffee particles together, the whole coffee bed forms a giant "cage," and the released carbon dioxide has nowhere to escape. It accumulates inside the bed and creates that bulging phenomenon.

The hot water injected during the main extraction phase breaks that cage open, letting carbon dioxide escape. That is why we see plenty of foam when we pour after the bloom. With the Volcanic Brew, however, each pour carries very little water and moves in a small circle, so only a small portion of the carbon dioxide is released each time. Naturally, we keep seeing foam rise with every pour, because the carbon dioxide never fully escapes.

To create this visual effect, the beans must meet two conditions: an extremely high expansion rate and abundant carbon dioxide. So this method is not suited to light roast coffees, which are dense, expand little and hold little carbon dioxide. It is mainly used for dark roast beans, since it was originally designed specifically for brewing dark roasts.

Exceptional Sweetness of Volcanic Brew

Next, FrontStreet Coffee will share the second characteristic of the Volcanic Brew: the resulting coffee has exceptionally high sweetness.

Why does dark roast coffee brewed this way taste so sweet? The Volcanic Brew is famous not only for its coffee bed behavior but also for the sweetness it produces. That comes mainly from its distinctive approach: high concentration with low extraction. A large dose with a small water volume is standard for almost every classic Japanese brewing method. At a time when measuring tools were not widespread, this was arguably the best way to avoid bitterness. By reducing the amount of hot water poured, you limit what can be extracted and thereby hold back the bitterness.

Small water volume inevitably means lower extraction efficiency in terms of the quantity of water. So to pull enough flavor compounds out of the coffee, other parameters have to be improved to raise extraction efficiency, which is what led to pouring small amounts of water multiple times. The essence of coffee extraction is using water as a solvent to contact the grounds and then drawing soluble substances out of the coffee along a concentration gradient. The fewer substances the water already contains, the more coffee compounds it can extract. Small, repeated pours ensure that the water contacting the grounds each time is low in concentration, which naturally improves extraction efficiency.

Meanwhile, the gaps between pours extend the total extraction time. More time gives water and grounds more contact, further improving efficiency. Too many segments or too much time, though, can easily extract compounds we do not want. So the grind needs to be a little coarser here, allowing the grounds to avoid releasing bitter, astringent compounds even during a prolonged extraction.

Alright, without further ado, let FrontStreet Coffee share how to execute the classic Volcanic Brew.

How to Execute the Volcanic Brew

First, choose a suitable dark roast coffee. On FrontStreet Coffee's bean list, FrontStreet Coffee's Golden Mandheling is clearly the most appropriate. Under a dark roast it emits a unique deep woody aroma, black chocolate flavor and exceptional sweetness, simply irresistible. Based on the principles above, FrontStreet Coffee's Volcanic Brew uses the following parameters:

Beans used: FrontStreet Coffee's Sumatra Golden Mandheling (Dark Roast)
Coffee amount: 20g
Grind setting: Ek43 at 11 setting (60% pass-through rate on #20 sieve, coarse sugar texture)
Coffee-to-water ratio: 1:12
Brewing temperature: 88°C
Filter used: Kalita trapezoid filter cup

Although there will be many pours, the whole process actually divides into two parts: the bloom and the continuous multiple pours. So the first step is still the bloom. Use 40ml of hot water, and more is unnecessary, with the time still 30 seconds.

Once the bloom ends, we move into the small, multiple pours. Each pour is 20ml, poured in small circles at the center of the filter. The interval between pours should be the moment you see the coffee bed is about to collapse, roughly 5 seconds. During brewing, you will keep seeing the whole bed rise and fall, with bubbles surfacing at the spot where the hot water lands, a genuine volcanic eruption.

After extraction ends, we cannot drink the coffee directly, because we used less water and the concentration is extremely high. Most people would find such a strong cup hard to accept. So we need to dilute it with additional water to bring the concentration into an acceptable range.

Typically, FrontStreet Coffee adds 50-60ml of hot water for dilution, producing a coffee of moderate concentration, neither too strong nor too weak. When you taste it, you can clearly pick up pine and spice aromas, prominent caramel sweetness and a rich black chocolate fragrance. The overall body is moderate, but the mouthfeel is smooth and gentle. Simply put, it is extremely comfortable to drink, without any burden.

If you also enjoy dark roast coffee, why not try this simple brewing method that delivers maximum visual and emotional satisfaction? You will enjoy the show while you brew, and you will end up with a cup of exceptionally sweet coffee.

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FrontStreet Coffee Recommendation

The Volcanic Brew leans on beans that expand strongly and hold plenty of carbon dioxide, which is exactly what a dark roast delivers. FrontStreet's Sumatra Golden Mandheling, the bean used above, fits the method perfectly: a dark roast gives it deep woody aroma, black chocolate flavor and exceptional sweetness, and its low acidity and long, thick body suit drinkers who like bold coffee without sourness. The Golden Mandheling comes from Indonesia's PWN company, which applies strict standards: beans must be 18 mesh or larger, and a 300g green sample may contain fewer than three defective beans, meeting the top G1 grade, followed by three rounds of hand sorting to remove every remaining defect. That is what gives it a particularly clean cup and a stronger sweetness.

If you prefer a more affordable way to try dark roast pour-over, FrontStreet's Lintong Mandheling is the daily-drinker option. Grown around Lake Toba in North Sumatra between 1,100 and 1,600 meters and wet-hulled, it is full and rich, sweet-bitter with a powerful entry, showing clove and woody aromas, along with the low acidity, spice and mint-like notes typical of a medium-dark Mandheling.

For something outside Sumatra, FrontStreet's Jamaica Blue Mountain No. 1 is a good dark-roast companion to this style of brewing. A Typica variety grown in the Blue Mountains, it is the most balanced of coffees, neither aggressively acidic nor heavily bitter, with cream, caramel, chocolate, nut and honey notes, a smooth, rounded entry and a clean, long finish.