: Finer grinds reduce permeability, slowing the flow.
: New equations now account for the surface area-to-volume ratio and the "polydispersivity" (variation in size) of the grounds. This allows baristas to predict mass flow rates based on grind size and "tamped" density. 3. Particle Physics: The Fines Debate the physics of filter coffee epub updated
: A 2024 study identifies a "transition" point where water flows just slow enough to absorb maximum flavor but fast enough to avoid "backing up". : Finer grinds reduce permeability, slowing the flow
| Variable | Physics Principle | Target Range | |----------|------------------|---------------| | Grind size | Permeability & extraction rate | Medium-fine (700–900µm) | | Water temp | Diffusion coefficient | 90–96°C | | Ratio (coffee:water) | Concentration gradient | 1:16 to 1:18 | | Pour structure | Agitation & boundary layer | 4–5 pulsed pours | | Total time | Extraction completeness | 3:00–3:45 min | | Filter type | Particle retention | Rinsed paper | published by Scott Rao Coffee Books
is a seminal scientific exploration of coffee brewing, published by Scott Rao Coffee Books