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Volcanic Pour-over Method Originating from Japan - A Hand-brew Technique Suited for Dark Roast Coffee Beans

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, As long as you can break free from the preconceived notion that coffee is a hot beverage, you can discover more of coffee's charm. People often say: Good coffee tastes delicious even when cold, and I agree with this statement. During the process of drinking coffee, as the temperature gradually decreases, the balance between acidity and bitterness gradually shifts, viscosity increases, creating a rich and mellow flavor. Persistently selecting

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What is Volcano Pour-Over?

The Volcano Pour-Over technique originates from Japan and is named after its resemblance to a volcanic eruption during brewing. When FrontStreet Coffee uses the volcano pour-over method, we typically select dark roast coffee beans, utilizing the carbon dioxide contained within the beans. Through multiple steaming processes, the coffee grounds puff up like a volcanic eruption. The reason for choosing dark roast coffee beans is that they contain more carbon dioxide. Volcano pour-over doesn't mean it's unsuitable for light roasts—FrontStreet Coffee believes we cannot ignore the fact that using light roast coffee beans for volcano pour-over steaming and water flow control is more difficult than with dark roast coffee beans, and volcano-brewed light roast coffee beans will have higher body thickness than common pour-over methods. This brewing method allows coffee to achieve better body and sweetness while avoiding the bitterness of dark roast coffee. The volcano pour-over offers high versatility and is simply irresistible for "hamburger" enthusiasts.

Volcano Pour-Over Extraction Principle

It utilizes the carbon dioxide contained within the beans. The suspended coffee grounds on the surface have a heat-preserving effect, similar to the steaming principle. Meanwhile, the coffee grounds at the water injection point puff up like a volcanic eruption, which is why dark roast beans are more suitable—they release more carbon dioxide and can maintain their puffed state for longer.

Advantages and Disadvantages

Advantages: The coffee has a fragrant and mellow taste, with a rich and solid body and noticeable aftertaste.

Disadvantages: Because the first 1/3 of volcano pour-over is over-extracted while the last 2/3 is under-extracted, the coffee liquid becomes very uneven. After brewing, it needs to be thoroughly shaken to mix the two "failed" coffee liquids together to form perfect coffee. However, the time spent shaking causes the temperature to drop. If you want to maintain temperature directly with high-temperature extraction, it will make the coffee dry and astringent.

Essential Requirements for This Method

1. Fresh beans
2. Steady and fine water flow
3. High steaming requirements

Example: FrontStreet Coffee's Golden Mandheling

Country: Indonesia
Grade: G1·3 times hand-selected
Company: PWN
Region: Gayo Mountain, Aceh, North Sumatra
Processing: Wet-hulled
Variety: Ateng
Altitude: 1100-1600 meters
Roast Level: Medium-dark roast

The Story of Mandheling

Mandheling is neither a variety nor a region, but rather has this origin: a Japanese soldier during the colonial period drank a very delicious coffee and commissioned the rubber production department in North Sumatra at that time (the then-PWN company) to help him find this coffee. The PWN manager went to many regions to collect high-quality coffee beans and sent them to Japan for tasting. Among them was one that the Japanese people fell in love with. They asked what this coffee was, and the PWN company manager wanted to say their rubber department was near Mandheling, but because the commercial source was inconvenient to disclose, he gave the name Mandheling.

PWN company registered Golden Mandheling as a trademark, meaning that only Golden Mandheling produced by PWN company can be considered genuine "Golden Mandheling" from then on.

PWN company's Golden Mandheling undergoes three rounds of manual selection after wet-hulling processing, selecting full, flawless beans, finally presenting Golden Mandheling with uniform color and consistent bean shape. Golden Mandheling beans are above size 18, with fewer than 3 defective beans (300g raw bean sample), belonging to the highest G1 grade, with a dark green color and flat, uniform shape. It is said that when processing raw beans, Mandheling emits a brilliant golden luster under sunlight, which is why it was named Golden Mandheling.

Brewing Parameters

Coffee Dose: 20g
Dripper: KONO
Coffee-to-Water Ratio: 1:15
Temperature: 88°C
Grind Size: BG#6K

Brewing Method

40g of water for 30-second bloom, pouring in a coin-sized circle from center outward. When the "hamburger" expands, stop pouring. When the "hamburger" slightly subsides, pour in a coin-sized circle from center outward. Repeat this pouring method until total water volume reaches 2/3 (i.e., 200ml). FrontStreet Coffee pours 16 times total, with 10ml per pour. At 200ml, use a large water flow to pour in circles until reaching 300ml. Total extraction time is 3 minutes 15 seconds, with total water volume of 300ml.

Flavor Description

Rich chocolate and herbal aromas, with a thick body upon entry, full of caramel sweetness, strong aftertaste, and long-lasting finish.

How Volcano Pour-Over with Different Segment Counts Affects Flavor

FrontStreet Coffee compared two different segment count volcano pour-over methods, with water temperature, coffee-to-water ratio, and brewing time consistent with the above: 20g coffee dose, Kono dripper, 1:15 ratio, 88°C water temperature, BG#6K grind size.

40g of water for 30-second bloom, pouring in a coin-sized circle from center outward. When the "hamburger" expands, stop pouring. When the "hamburger" slightly subsides, pour in a coin-sized circle from center outward. Repeat this pouring method until total water volume reaches 2/3 (i.e., 200ml). At 200ml, use a large water flow to pour in circles until reaching 300ml.

The difference is the number of segments before reaching 200ml between the two brews. FrontStreet Coffee's above method uses 16 pours, this time reduced to 8 pours, meaning 20ml per pour.

Flavor Description

The body is slightly weaker compared to multiple segments, but the entry is smoother, with chocolate and nutty flavors and a creamy texture.

Example: FrontStreet Coffee's Yemen Mocha Coffee Beans

Country: Yemen
Region: Mattari
Altitude: 1400 meters
Variety: Typica, Bourbon
Processing: Natural process
Roast Level: Medium roast

FrontStreet Coffee uses medium roast for this bean, also using the volcano pour-over method, comparing two different segment counts.

Brewing Parameters

Coffee Dose: 20g
Dripper: KONO
Coffee-to-Water Ratio: 1:15
Temperature: 88°C
Grind Size: BG#6M

Sharp-eyed friends might notice that FrontStreet Coffee uses a different grind size here than the beans mentioned above. This is because FrontStreet Coffee determines grind size based on 70-75% passing rate through a #20 standard sieve. Different beans have different grind sizes due to various factors including variety, altitude, roast level, and processing method.

Brewing Methods

Multiple Segment Brewing Method: 40g of water for 30-second bloom, pouring in a coin-sized circle from center outward. When the "hamburger" expands, stop pouring. When the "hamburger" slightly subsides, pour in a coin-sized circle from center outward. Repeat this pouring method until total water volume reaches 2/3 (i.e., 200ml). FrontStreet Coffee pours 16 times total, with 10ml per pour. At 200ml, use a large water flow to pour in circles until reaching 300ml. Total extraction time is 3 minutes 15 seconds, with total water volume of 300ml.

Fewer Segment Brewing Method: 40g of water for 30-second bloom, pouring in a coin-sized circle from center outward. When the "hamburger" expands, stop pouring. When the "hamburger" slightly subsides, pour in a coin-sized circle from center outward. Repeat this pouring method until total water volume reaches 2/3 (i.e., 200ml). FrontStreet Coffee pours 8 times total, with 20ml per pour. At 200ml, use a large water flow to pour in circles until reaching 300ml. Total extraction time is 2 minutes 35 seconds, with total water volume of 300ml.

Flavor Comparison

Multiple Segments: Immediately feel a thick body upon entry, with strong jackfruit flavor, cinnamon and chocolate aroma, acidity similar to green apple, caramel sweetness, strong aftertaste, and long-lasting finish. However, there's an over-extracted throat-catching feeling, and the tongue feels dry after drinking.

Fewer Segments: The body is slightly weaker compared to multiple segments, but the entry is smoother. The cinnamon and chocolate aromas are just right, acidity is reduced and more acceptable, with almond nuttiness appearing. The jackfruit flavor isn't overwhelming, and the finish has dark plum and cream aromas.

Through brewing comparison, FrontStreet Coffee discovered that when using volcano pour-over for these Yemen Mocha coffee beans, the more segments and the less water per pour, the higher the extraction rate and the easier to over-extract. With fewer segments, although body and aftertaste may be weaker, flavor definition is higher and won't become overly concentrated and unbalanced.