The Differences Between Flannel Drip Coffee and Regular Pour-Over Coffee, the History of Flannel Filter Cloth, and What Are the Characteristics of Flannel?

Flannel filters can be said to represent a traditional symbol of Japanese-style coffee brewing! Whether in books or various media videos, we often see Japanese people holding the filter cloth in their left hand, gripping the coffee pot in their right hand, and earnestly brewing coffee with focused attention.

Witnessing such dedicated posture inevitably makes one wonder - what charm does this filter cloth possess that captivates them so deeply? Could it be that the coffee brewed with it tastes better than coffee brewed with paper filters?

History of Flannel Filters

Flannel fabric first appeared in France, but the original flannel was not the material we use today - it was made from wool. It wasn't until later when cotton materials emerged that flannel evolved into being woven from coarse wool! Regarding the use of flannel fabric, the French typically used them as container covers. When flannel was introduced to Japan, the Japanese people, who love to study extraction methods, discovered its filtering properties, thus pioneering the cultural tradition of using flannel as a filtering tool.

In the modern era where paper filters are prevalent, Japanese people still indulge in brewing coffee with flannel filters, which must mean there are characteristics that flannel can achieve but paper filters cannot!

Characteristics of Flannel

Let's first consider the characteristics of paper filters: First, they are affordable - a pack of 100 paper filters typically costs around 30-40 yuan, averaging about 0.3-0.4 yuan per filter. Second, they offer excellent filtration! Coffee brewed with paper filters has no residue or impurities! Compared to any other coffee filtering tool, the coffee it filters is much cleaner!

Obviously, the first characteristic cannot be compared, as this concerns brewing rather than price! Secondly, although flannel filters are more expensive, they can be reused repeatedly as long as they are properly cleaned! Therefore, the key lies in the second characteristic of paper filters - filtering performance! Because flannel is woven from cotton material, its gaps are much larger compared to paper filters, which allows oils and other insoluble substances to pass through these gaps into the lower pot. This is a characteristic that paper filters cannot achieve. So, what changes do these substances cause when they drip into the lower pot?

That's right! They increase the body of the coffee! In Japan, where dark roasted coffee is popular, body is a very important characteristic of this type of coffee, and coffee brewed using flannel as a filtering tool has precisely this advantage. Additionally, the flannel filter brewing method requires a certain degree of patience. In the past, because almost all dark roast coffee beans were used, which were extremely prone to over-extraction, and since most brewing parameters couldn't be measured (water temperature, liquid weight), people needed to concentrate intensely on visually controlling all brewing parameters: water flow height, water flow rate, coffee liquid weight, and so on. This brewing method, which requires full dedication to produce a pot of delicious coffee, perfectly aligns with the Japanese spirit of craftsmanship, and thus, they and the filter cloth became a perfect match!

Almost all coffee shops began using flannel filters, and then people who visited these coffee shops were captivated by this highly visual and craft-oriented flannel brewing process. When they returned home, they also started using flannel as a filtering tool for coffee extraction. Word spread from one to ten, then from ten to a hundred, and flannel filters spread throughout Japan until the later popularity of filter drippers and paper filters gradually reduced the usage proportion of flannel filters.

How to Brew with Flannel Filters

First, there's the choice of whether to hold by hand. If you want to personally experience traditional Japanese-style brewing, then holding the flannel by hand is an essential movement. However, if you want to reduce hand fatigue, you can certainly choose a stand to elevate the flannel filter, although this reduces much flexibility.

In terms of coffee bean selection, because flannel is more difficult to extract light roast beans, generally dark roast beans are preferred. To avoid over-extraction, the grind is usually somewhat coarser, around 60-65% on a #20 sieve. Secondly, the gaps in flannel are much larger, so the drainage speed is faster. Therefore, during brewing, you must not only prevent over-extraction bitterness caused by high-temperature brewing but also guard against under-extraction due to too fast flow rate.

Therefore, flannel brewing uses more coffee grounds, then uses a small amount of hot water with a fine water flow to extend the extraction time, thereby increasing concentration while avoiding the bitter taste of over-extraction (high concentration, low extraction)! Generally, a single-serve filter cloth uses about 20-25g of coffee grounds! The water temperature is around 88°C. Hand-held flannel brewing cannot measure the powder-to-water ratio, so typically the powder-to-liquid ratio is used instead of the powder-to-water ratio for calculation. The powder-to-liquid ratio for hand-held flannel is 1:10, which converts to a powder-to-water ratio of 1:12. (For details on the conversion reason, refer to this article: The relationship between powder-to-water ratio and powder-to-liquid ratio). During brewing, first use a small amount of hot water for blooming, then continuously pour water into the center with a small water flow (slow small circles) until the coffee liquid in the lower pot reaches the target amount, then remove the filter cloth - brewing is complete!

It's worth noting that we need to disinfect and clean the flannel filter both before and after brewing! Pre-brewing disinfection removes negative flavors attached to the filter cloth, while post-brewing disinfection allows the filter cloth to be reused. The general disinfection method is to boil it in boiling water for about five minutes, then rinse with cold water and finally wring dry.

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