Analysis of Siphon Coffee Brewing Pros and Cons | Siphon Coffee Brewing Experience Sharing and Learning

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The siphon pot is not only beautiful to look at but also a pleasure to watch in action. Siphon coffee expresses a coffee's flavor especially well, highlighting the taste differences between single origins and producing a richer, more full-bodied cup. Because its heat source raises the temperature gradually, the brew moves through high, medium, and low temperature ranges, generating a wealth of flavor variation. Some friends, though, run into trouble when using a siphon. Today, FrontStreet Coffee will share some extraction insights about this striking piece of equipment.

Siphon Pot Principle

Although it is called a siphon pot, it does not actually extract by the siphon principle at all; it relies on the pressure difference created by thermal expansion and contraction. The structure consists mainly of a stand, a lower pot, and an upper pot. In the diagram below, you can see that the stand connects to and supports the lower pot. The lower pot holds and heats the liquid and is roughly spherical, which ensures more even heating. The upper pot is cylindrical with an extended, slender pipe, and the pipe's contraction point carries a rubber ring - a crucial core component.

The extraction process is quite simple. First, fill the lower pot with water and heat it, then place the upper pot into the lower pot without securing it tightly. As the temperature rises, the water expands and accelerates into steam. At this point, secure the upper pot tightly, creating a vacuum in the lower pot. The steam compresses the space in the lower pot, causing the hot water to continuously climb through the pipe under pressure. While the hot water sits in the upper pot, we can begin adding coffee grounds to carry out mixed extraction.

Once extraction is complete, remove the heat source. As the temperature falls, the steam in the lower pot begins to contract and the pressure returns to normal. The coffee liquid in the upper pot then flows back down to the lower layer, while the grounds in the liquid are held back in the upper pot by the filter. When the coffee liquid has fully flowed down, extraction is complete.

Built on the immersion extraction method, the siphon pot's biggest characteristic is its relatively high extraction rate. Siphon-extracted coffee typically has a rounder, smoother mouthfeel and a very full-bodied texture. This comes mainly from the vacuum created during extraction and the use of filter cloth, both of which help produce coffee with a more substantial texture. These qualities happen to bring out the best in medium to dark roast beans.

So if you are using a siphon to extract coffee, FrontStreet Coffee recommends FrontStreet Coffee's Paradise Bird, Queen Manor, Golden Mandheling, Blue Mountain No.1, and Huilan coffee beans.

Siphon Pot Misconceptions

Because the most conventional approach is to heat the water in the lower pot until it bubbles continuously before starting extraction, most people believe siphon coffee is extracted at 100°C. There are actually two misconceptions here. First, siphon coffee is not extracted at 100°C.

In traditional methods, although the lower pot is heated until it bubbles continuously, the hot water has not yet reached boiling point at that stage - at most around 96°C. The bubble chain simply accelerates bubble formation. Then, when the hot water moves from the lower pot to the upper pot under pressure, it loses heat to the upper pot's material and to the surrounding environment. FrontStreet Coffee measured the hot water reaching the upper pot and found the temperature to be only around 92-93°C.

Another misconception concerns the point at which the pressure difference forms. Water does not need to be heated to boiling to produce steam and pressure. Water evaporates at any temperature; at lower temperatures it simply evaporates more slowly. If we secure the upper pot before frequent bubbling begins, the hot water will still be pushed up to the upper pot, just at a relatively slower speed.

In other words, siphon extraction temperature is not a single fixed value. We can decide the water temperature to use based on the extraction time we want or the roast level of the coffee being extracted.

For example, if we want a longer extraction time, or we are extracting a light roast that is difficult to extract, we can use a higher temperature. If we are extracting darker roasted beans, or we want a longer extraction, we can let the water temperature be lower. The same logic applies to grind size: longer extraction time and darker roast call for a coarser grind; shorter extraction time and lighter roast call for a finer grind. (Note, though, that even at its coarsest, siphon grinding is still finer than pour-over grinding.)

Siphon Pot Filtration Tools

Besides the stand, upper pot, and lower pot, the siphon contains one small tool - the filtering device attached to the bubble chain. It can be fitted with different filters depending on your preference: filter paper, flannel filter cloth, or other filters such as non-woven fabric. (The bubble chain has many uses, such as helping us better observe temperature changes and preventing violent boiling, which is why we need to seat the upper pot properly from the beginning.)

In the article "The Difference Between Filter Paper and Filter Paper is Greater Than the Difference Between Humans and Chimpanzees," FrontStreet Coffee noted that these material differences not only change water seepage speed but also determine how much oil and how many particles are retained in the coffee liquid.

Filter paper has the highest precision, so when we use it the siphon coffee comes out relatively clean, with stronger flavor recognition on the palate. The downside is that it is too clean, lacking the soul of siphon coffee - as readers pointed out in the comments. So generally, when we make coffee for ourselves and do not mind the trouble, FrontStreet Coffee recommends flannel filter cloth as the filtration tool for siphon coffee.

Flannel is expensive and relatively troublesome to clean, but its advantage is that it possesses the soul of siphon coffee: it can retain the coffee's oils and some particles in the liquid, giving the coffee a richer aroma and a more full-bodied texture.

Siphon Pot Coffee Grounds Addition Sequence

There are two ways to add coffee grounds in siphon coffee: "pre-addition" and "post-addition." Pre-addition means adding the grounds to the upper pot before the hot water rises under the pressure difference, then waiting for the water to rise for extraction. Post-addition means adding the grounds after the hot water has fully risen to the upper pot, then mixing for extraction.

(The following image shows post-addition.)

Each method has its advantages, but in general FrontStreet Coffee recommends that beginners use the post-addition method, because it has fewer variables and produces relatively even extraction. With pre-addition, the extraction of the grounds differs according to the order in which they contact the water. That can bring more layers, but it also places higher demands on the operator.

Siphon Pot Stirring Methods

When you buy a siphon pot, besides the main body described above, it also comes with a stirring rod. This is because siphon extraction is immersion extraction, so stirring is part of the process.

There are many stirring methods, such as the tapping method, the circular method, the cross method, the Z-shaped method, and even the infinity-shaped method. Apart from the tapping method, the others stir relatively strongly, which can significantly increase the extraction rate, depending on the force and speed used. The tapping method uses taps to push the grounds into the water, mainly to fully wet them. You can choose which methods to use based on your extraction approach, with no need to stick to only one.

Auxiliary Tools for Siphon Pot

Besides the tools above, extracting siphon coffee also requires two additional items: cloth and a heat source.

We need two cloths in total: one dry and one wet. The purpose of the dry cloth is to prevent explosions. Before heating the lower pot, we need to wipe off any moisture on it; otherwise the moisture can create a real risk of the pot exploding during heating. The purpose of the wet cloth is to control the speed at which the coffee liquid returns, which we will cover later, so we will not say more here.

There are many choices for a heat source - a gas stove, a light-wave oven, or an alcohol lamp, as long as it can heat. Common gas stoves and light-wave ovens can control heat intensity, with relatively fast and stable temperature rise, though the cost is somewhat higher. Alcohol lamps are inexpensive but provide a smaller, less stable heat source and take longer to heat. Either way, they all work, so use whatever you have - though FrontStreet Coffee suggests that with an alcohol lamp it is best to add hot water rather than room-temperature water to the lower pot, or the heating time becomes really long.

FrontStreet Coffee Recommendation

The siphon's high extraction rate and cloth filter make it a natural match for medium to dark roasts, which is exactly why FrontStreet Coffee points siphon users toward its fuller-bodied beans. The FrontStreet PWN Golden Mandheling is roasted dark for a low-acidity cup that is thick and long, packed with herbal and dark chocolate notes and a faint earthy undertone that suits anyone who likes a heavier, less acidic coffee.

For a rounder, sweeter option, the FrontStreet Brazil Queen Manor brings low acidity, a very balanced body, prominent nut and cocoa aromas, and clear caramel sweetness, smooth and warm on the way down and well suited to a siphon, an espresso, or a moka pot. If you want the classic balanced profile, the FrontStreet Jamaica Blue Mountain No.1 layers hazelnut, cream, chocolate, caramel, honey, and a light fruit note without any one of them dominating. And the FrontStreet Papua New Guinea Paradise Bird, grown from the same Typica variety as Blue Mountain at 1600-1800 meters on volcanic soil, is a clean, sweet, low-acidity single origin with an AA grade and a body close to Blue Mountain's.