The Mechanics and Philosophy of Tetsu Kasuya's 4:6 Method
Introduced by 2016 World Brewers Cup Champion Tetsu Kasuya, the 4:6 Method revolutionized manual pour-over brewing by establishing a clear causal relationship between pouring intervals and sensory attributes. Built on the philosophy of repeatable brewing without complex turbulence acrobatics, the recipe divides the total water into two distinct phases.
1. The 40/60 Functional Division
☕ The First 40% (Taste: Balance of Sweetness & Acidity)
The first two pours define the cup profile. For 20g coffee and 300ml total water, 40% equals 120ml.
• Sweetness Emphasis: Pour 1 = 50ml, Pour 2 = 70ml (a smaller bloom allows caramelized sugars to dissolve deeply).
• Acidity Emphasis: Pour 1 = 70ml, Pour 2 = 50ml (a larger bloom rapidly pulls bright malic and citric organic acids).
• Balanced Standard: Pour 1 = 60ml, Pour 2 = 60ml (the default configuration in our timer).
💧 The Latter 60% (Strength: Body & Concentration)
The remaining 180ml dictates the final concentration (TDS) based on the number of pours:
• 3 Pours (60ml each): Standard rich medium body and smooth finish (Recommended gold standard).
• 2 Pours (90ml each): Light, clean, tea-like texture.
• 4 Pours (45ml each): Heavy, velvety, concentrated mouthfeel.
2. Grind Size & Flow Control: Why Coarse Grind is Mandatory
Conventional V60 methods utilize a medium-fine grind and steady circular turbulence. In contrast, the 4:6 method requires a distinctly coarse grind (comparable to French Press or coarse cupping grind, ~1000 to 1200 μm).
Because each 45-second interval allows the brew water to fully drain into the carafe before the next pour, using fine grounds would compact the coffee bed, leading to severe clogging and bitter over-extraction. A coarse grind maintains rapid drainage, preventing spent grounds from over-steeping.
3. Frequently Asked Questions (FAQ)
A. If water sits on the bed past 45 seconds, your grind size is too fine or your grinder produces excessive micro-fines. Move your grinder 2~3 notches coarser.
A. Kasuya explicitly advises against swirling the dripper. Swirling migrates fine coffee particles down to the paper tip, choking the filter and slowing drainage.
A. 92°C to 94°C (198°F~201°F) for light to light-medium roasts. For darker roasts, lower to 88°C~90°C (190°F~194°F) to avoid extracting astringent tannins.