| Variable | Physical role | Practical effect | |---|---:|---| | Temperature | Affects solubility & extraction rate | Higher temp → faster extraction; risk of bitterness if too hot | | Grind size | Controls surface area & permeability | Finer → stronger, faster extraction; coarser → weaker, slower | | Flow rate / Brew time | Sets contact time & removal of solubles | Faster flow → shorter time → under-extraction | | Filter type | Controls particle/oil retention | Paper → clean cup; metal → fuller body | | Pour technique | Influences turbulence & saturation | Even pour → consistent extraction; poor pour → channeling |
Freshly roasted coffee contains up to 2% of its weight in CO₂ trapped in the cellular matrix. This gas obeys Henry’s Law: at higher temperatures, the solubility of CO₂ in water decreases, leading to violent outgassing.
Problem: Sour & Weak (underextracted)
Problem: Bitter & Dry (overextracted)
Problem: Long drawdown (>4 min for 250 mL)
Problem: Fast drawdown (<2 min for 250 mL)
Most home brewers lose 6–10°C between the kettle and the slurry. A physics-based PDF analyzes the coffee bed as a thermal capacitor. The Physics Of Filter Coffee Pdf
The coffee slurry is a porous medium. Water flows through interstitial spaces between particles. The flow rate is governed by Darcy’s Law:
$$Q = \frac-kA\mu \frac(P_b - P_a)L$$
Where:
Key Takeaway: Flow rate is directly proportional to the square of the particle size. If you double the grind size, the flow rate increases roughly four-fold.
Filter coffee is where physics meets morning ritual. Below is a concise, engaging post that explains the key physical principles behind brewing great filter coffee, suitable for a blog or social post.
When you pour water from a gooseneck kettle into a coffee bed, you are injecting kinetic energy into a porous medium. The physics begins with the jet break-up. | Variable | Physical role | Practical effect
Standard starting point: 1:16.67 (i.e., 15 g coffee : 250 g water)
Never measure water in milliliters as if equal to grams? Actually, 1 mL water ≈ 1 g at room temperature – safe.