The Complete Guide to Pour-Over Coffee: Paper Filter vs. Flannel Drip Methods Explained

The Science of Coffee Crema: Why Some Methods Capture It Better Than Others

Recently, a customer was enjoying a cup of Mandheling coffee and remarked, "This Mandheling is incredibly clean, but it lacks crema—the mouthfeel is somewhat lacking." He then recalled the Mandheling he had during his travels to Japan, remembering the gleaming layer of crema on the surface and its remarkable mouthfeel...

Actually, whether you can extract coffee crema has little to do with technique—it's primarily related to the filtering material used. Nowadays, pour-over coffee typically uses filter paper as the filtering medium. Filter paper has extremely strong filtering capabilities, capable of filtering out all solid particles and most oils. Therefore, coffee brewed with filter paper will be exceptionally clean.

If you want to preserve coffee's crema, you need materials with less intense filtering properties, such as flannel or metal mesh. Due to their larger mesh gaps, metal filters allow not only oils to pass through but also some fine coffee grounds, making them less commonly preferred as filtering materials.

Flannel's fiber gaps, however, are just right. Flannel is a type of fabric with one cotton side and one fleece side. Its greatest characteristic is that it can filter out all solid coffee grounds while allowing coffee oils to pass through. Therefore, using flannel filters to brew coffee excellently preserves the coffee's crema. This layer of coffee oil makes the coffee smoother, fuller, and richer in the mouth.

The Historical Journey of Flannel Coffee

The use of flannel for filtering coffee dates back to 18th century Europe. At that time, boiled coffee was popular—coffee grounds were placed in a pot and boiled with water, then filtered through flannel cloth to remove the grounds. This method continued until the emergence of pour-over coffee, which then spread to Japan.

The Japanese discovered that compared to filter paper of that era, flannel produced cleaner coffee with a richer mouthfeel. Additionally, it could be cleaned and reused, resulting in lower per-cup costs. Flannel coffee once swept through East Asia, and even today, many coffee shops in Japan continue to insist on using flannel for their coffee service.

Why Flannel Has Been Replaced by Filter Paper

Nowadays, flannel has been largely replaced by filter paper, with very few coffee shops still using it to brew coffee. This necessitates discussing the limitations of flannel.

Flannel Isn't Suitable for Light Roast Coffee

Compared to filter paper, flannel's gaps are much larger, making its water flow rate significantly faster than paper. Moreover, flannel cloth allows coffee liquid to pass through from all sides, meaning the higher the water level, the faster the flow rate.

Therefore, baristas using flannel typically use a full dose of coffee, first moistening the grounds with drops or a small water stream, then pouring water in a small circular motion at the center to avoid water flowing away from the sides.

The biggest difference between filter paper and flannel is that paper allows water to remain longer, creating an immersion extraction. Flannel, with its weak water retention capacity, relies entirely on filtration extraction throughout the process.

When brewing dark roast coffee using a slow-paced, long extraction method, you can achieve a more complete flavor profile—resulting in sweet, bitter, and rich characteristics.

When using flannel to brew light roast coffee, if you still employ the slow-paced, long extraction method, while the coffee extraction may be complete, it will suppress the bright acidity of light roasts, creating heavy, thick flavors similar to black tea or cane sugar.

If you brew it the same way as with filter paper, even adjusting the grind size to slow down the water flow, the final coffee flavor will still lean toward tea-like notes, weak acidity, and poor clarity.

In the wave of light roast coffee popularity, flannel's advantages are difficult to demonstrate, instead exposing its weaknesses.

Differences in Flannel Brewing Technique

Building on the previous issue, flannel brewing methods differ significantly from paper filter and pour-over techniques. To brew well with flannel, one generally needs to relearn and understand its usage methods. Furthermore, flannel brewing relies heavily on experience and is difficult to quantify with data. This undoubtedly increases the learning curve for most baristas who start with data-driven approaches.

Flannel is Difficult to Store

Although flannel has a higher unit cost, it can be reused through proper storage. However, storing flannel properly is quite challenging. First, flannel cannot be dried, because the process of wetting and then drying damages the fiber structure. Therefore, after using flannel filters, you need to clean them thoroughly and then store them in clean water, sealed and refrigerated to prevent bacterial growth.

However, with increased usage (typically starting from the third use), the filters gradually accumulate coffee stains, turning yellow and darker. In subsequent uses, this can easily lead to hygiene issues and flavor contamination.

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