What Grind Size Works for Blue Mountain Coffee in a Cloth Filter?
A flannel filter cloth has coarser pores than filter paper and holds back some of the coffee oils, so the cup tastes fuller and smoother. That suits the rich character of Blue Mountain coffee. A comparison of three grind sizes, BG-5R, BG-6M, and BG-6A, found BG-6A the most balanced and rich, while BG-5R ran strong with slight astringency and BG-6M came out thin.
The test used 20 grams of coffee, 85°C water, a 1:13 ratio, and a single pour. Brewing with a cloth differs from a KONO dripper because water flows outward in all directions, and the front and back sides drain at different rates. Clifton Farm, at 1,310 meters, is the only site in Jamaica holding the Rainforest Alliance certification mark.
Flannel filter cloth can retain coffee oils, making the mouthfeel richer and smoother, and is especially suitable for the full-flavored Front Street Blue Mountain coffee. But what grind size should be used when brewing with a cloth filter? Is it the same as the commonly used grind size for the KONO dripper? Front Street Coffee conducted a comparative experiment using three grind sizes, BG-5R, BG-6M, and BG-6A, with 20 grams of coffee, a water temperature of 85°C, a coffee-to-water ratio of 1:13, and a single-pour brewing method. The results showed that BG-5R was stronger with slight astringency, BG-6M had a thinner mouthfeel, while BG-6A performed in a balanced and rich way. The article also explains the reasons for the changes in flow rate of the flannel filter cloth and gives grind size recommendations for dark-roasted beans.
The editor has always felt that brewing coffee with a flannel filter cloth is a pretty cool thing. So today Front Street Coffee is going to use this cloth to brew a pot of Front Street Blue Mountain coffee. Then the question is: when brewing with a cloth filter, what grind size should be set? Is it the same as when using a KONO dripper to brew Front Street Blue Mountain as usual?
Flannel filter cloth by Front Street Coffee
The flannel filter cloth itself has pores coarser than filter paper and can retain some of the coffee oils, unlike filter paper, which blocks almost all the oils. Because of this, the coffee brewed with it is fuller and smoother, which matches well with the rich character of Front Street Blue Mountain itself.
During brewing, there is nothing blocking the flannel filter cloth around its sides, so the water in the cloth can flow directly outward in all directions. In addition, the flow rates on the front and back sides of the filter cloth are not the same. The editor chose the back side for brewing today.
Bean information by Front Street Coffee
Front Street Jamaica · Blue Mountain
Region: Jamaica Blue Mountain
Estate: Clifton Farm
Altitude: 1,310 meters
Processing method: Washed
Variety: Typica
Roast level: Medium-dark roast
Clifton Farm by Front Street Coffee
Clifton Mount is one of the oldest coffee-producing sites in Jamaica that is still in normal operation, and Clifton Farm is the only one in Jamaica to have obtained the Rainforest Alliance certification mark. The total planting area in the Blue Mountain region is only 6,000 hectares, so it is clearly impossible for all coffee labeled "Blue Mountain" to be produced there.
Clifton Farm is the largest estate in this area, but by international standards it is still a small-scale planting operation. Many estate owners are only small landholders, and their families have cultivated this land for two centuries. It is widely recognized as a world-class site producing high-quality Blue Mountain coffee.
Brewing experiment by Front Street Coffee
Front Street Coffee plans to first test with the grind size commonly used for the V60 dripper: BG-5R (56% passing through a Chinese standard No. 20 sieve) and the grind size commonly used for the KONO dripper: BG-6M (45% passing through a Chinese standard No. 20 sieve) to run a test. In this experiment, only the grind size will be changed, while other parameters and technique will be kept as consistent as possible.
Parameters & technique: 20 grams of coffee, water temperature 85°C, coffee-to-water ratio 1:13; using a single-pour brewing method, first bloom with 40 grams of water for 25 seconds, then pour in one continuous stream until about 260 grams and stop, and when the water level drops to almost exposing the coffee bed, remove the flannel.
[BG-5R (56% passing through a Chinese standard No. 20 sieve)]
Timing starts at blooming; extraction time is 2’20”
Flavor: aromas of cocoa and spice; on the palate, flavors of cocoa, cream, blueberry, caramel, and cedar, but slightly astringent, and the fruit acidity is relatively concentrated.
[BG-6M (45% passing through a Chinese standard No. 20 sieve)]
Timing starts at blooming; extraction time is 2’17”
Flavor: aromas of spice, nuts, and cream; on the palate, flavors of raspberry, blackberry, almond, and caramel, with a finish carrying faint floral notes and fermented fruit aromas, but the mouthfeel is thinner and on the light side.
The Front Street Blue Mountain coffee brewed with the [BG-5R] grind size has a slightly astringent mouthfeel. Because the grind is relatively fine and the extraction time is long, the brewed coffee is stronger and feels somewhat over-extracted, with the sour and bitter notes tasting a bit too concentrated.
When using the [BG-6M] grind size, although the brewed Blue Mountain coffee has a smooth mouthfeel, the overall body is relatively thin and the flavor is lighter. The editor wanted to increase the coffee's richness on the basis of [BG-6M], so the grind size was adjusted finer to [BG-6A (64% passing through a Chinese standard No. 20 sieve)], with other parameters and technique unchanged.
[BG-6A (64% passing through a Chinese standard No. 20 sieve)]
Timing starts at blooming; extraction time is 2’15”
Flavor: aromas of nuts and cream; on the palate, flavors of milk chocolate, sucrose, vanilla, citrus, mulberry, and cream, with a relatively rich mouthfeel and an overall balanced profile.
Summary by Front Street Coffee
When brewing with a flannel filter cloth, the flow rate is relatively fast when the water level is high. After the water level drops, the thicker wall of coffee grounds around the sides forms an obstruction, and in addition, ultra-fine particles cling to the mesh of the filter cloth, so the flow rate slows down.
Therefore, Front Street Coffee recommends that when using a flannel filter cloth with a single-pour technique to brew dark-roasted beans such as Blue Mountain, a medium grind size can be chosen to reduce the occurrence of over-extraction caused by finer coffee grounds and a slow flow rate during extraction.
The above content is compiled by CoffeeHunters, a coffee news website.
