Are Coffee Filters Effective? Can Coffee Filters Replace Filter Paper and Flannel Filter Cloth?

Because filter paper offers excellent comprehensive performance, it has become the mainstream filtering material for pour-over coffee today. However, filter paper is not the only filtering material available. Besides filter paper, there are also filtering tools made from other materials such as flannel and metal.

Different materials have distinct characteristics and properties. To brew a good cup of coffee using filtering tools made from different materials, we need to first understand their characteristics and properties. Since there are already many discussions about flannel filter cloths, today FrontStreet Coffee will share how to use a metal filter to brew a good cup of coffee.

Advantages and Disadvantages of Metal Filters

The metal filter that FrontStreet Coffee has is one purchased casually online, with a mesh size of 400, and its appearance is that of an inverted cone with a flat bottom. The filter itself consists of two layers: the inner layer is a 400-mesh filtering metal screen, while the outer layer simply serves to provide structural support.

The particle size corresponding to 400 mesh is 38 micrometers, which can be considered an extremely small pore size. Therefore, even if the coffee grounds are shaken after being poured in, very few coffee grounds will pass through the filter and fall out. However, compared to filter paper, this pore size is still somewhat larger, which brings us to one of its advantages: it can retain coffee oils, just like flannel, which is a significant enhancement for coffee.

Because coffee oils contain certain oil-soluble aromatic compounds, their presence adds aroma to the coffee. Additionally, oils can increase body, giving the coffee a richer mouthfeel. This is an advantage that filter paper lacks, as its filtering performance is too powerful, resulting in the filtration of oils along with other substances.

In addition to this, metal filters have another advantage: they are environmentally friendly and economical because they are reusable. Like flannel filter cloths, they only need to be rinsed and dried after use before they can be used again. Calculating based on one cup per day, the cost of the filter can be recovered in about 100 days, making it very cost-effective.

Now, let's discuss the disadvantages! The disadvantages of metal filters, like their advantages, stem from their filter pores. Although metal filters can release oils to enhance the coffee's aroma and mouthfeel, they can also let coffee grounds through. Because there are numerous coffee particles smaller than 38 micrometers, they can easily pass through the filter, affecting the coffee's texture and flavor.

If you're using a grinder that doesn't produce high-quality grounds and plan to use a metal filter for coffee brewing, it's best to use a flour sifter to remove some fine particles before brewing. Otherwise, the negative impact of excessive fine particles should not be underestimated. That's roughly the situation, so now FrontStreet Coffee will demonstrate coffee brewing using a metal filter and share what we need to pay attention to during the process.

Brewing Demonstration

Before starting the brewing process, FrontStreet Coffee would like to insert a note: the drainage speed of a metal filter increases as the water level rises. What does this mean? When your water level is higher, its drainage speed becomes faster.

FrontStreet Coffee discovered through testing that at high water levels, the drainage speed of a metal filter is much faster than that of a V60. Excessive drainage speed reduces the contact time between water and coffee grounds, easily leading to under-extraction. Therefore, during brewing, we need to reduce the pouring rate to prevent the coffee bed and water level from rising too high, which would cause excessively fast drainage and lead to the risk of under-extraction, resulting in thin body and weak flavor.

For this brewing demonstration, FrontStreet Coffee used Yirgacheffe washed beans—Gedeb, with extraction parameters identical to those used with filter paper:

Coffee amount: 15g
Grind level: Ek43 setting 10, 80% pass-through rate on #20 sieve, approximately fine sugar size
Water-to-coffee ratio: 1:15 (15g coffee with 225ml hot water)
Brewing temperature: 92°C
Pouring method: Three-stage pour

The first step is still blooming—we first use twice the amount of water as the coffee grounds for a 30-second bloom.

After the bloom ends, we pour the second stage of hot water (in large circles), totaling 120ml. To prevent the water level from rising too high, we should pour with a small water flow at this point. At the same time, when circling, be careful to avoid the water stream hitting the edge of the filter, as this will cause bypass water.

When the coffee liquid has completely penetrated, we also pour the third stage of hot water with a small water flow, totaling 75ml. Since the extraction focus of this stage is the bottom layer of coffee grounds, we need to reduce the circular motion range, focusing on extracting the bottom layer of coffee grounds in the center.

When the coffee liquid has finished permeating, we can remove the filter cone and end the extraction! The total time was 2 minutes and 5 seconds, about 10 seconds faster than brewing Gedeb with filter paper. The flavor performance was excellent—delicate white floral notes, fresh lemon, and clean green tea aftertaste, presenting a very authentic Yirgacheffe flavor. In terms of mouthfeel, due to the presence of oils, this cup of Gedeb had a more outstanding richness, with a longer-lasting aftertaste, which was quite impressive.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473