Coffee: French Press — Immersion Brewing Parameters
French press immersion brewing uses a 1:15 brew ratio, 4-minute steep at 93–96°C, and coarse grind at 1000–1200 microns; metal filter retains coffee oils and micro-fines for a full-bodied result.
| Measure | Value | Unit | Notes |
|---|---|---|---|
| Brew ratio | 1:15 | Coffee to water by mass; 30g coffee per 450g water for a standard 3-cup press | |
| Steep time | 4 | minutes | Standard; some recipes extend to 8–12 min for intentional coarser grind |
| Grind size | 1000–1200 | microns | Coarse; coarser than any percolation method |
| Temperature | 93–96 | °C | Just off boil; temperature drops during steep |
| TDS range | 1.1–1.35 | % | Lower than espresso; slightly higher than typical pour-over due to fines |
| Oils retained vs paper filter | ~100 | % | Metal mesh retains essentially all cafestol, kahweol, and coffee lipids |
French press is one of the simplest and most forgiving coffee brewing methods. It requires no specialized equipment beyond the press itself, and its full-immersion approach produces a consistently full-bodied, rich cup. Understanding the differences between immersion and percolation brewing — and what the metal filter does and doesn’t remove — explains much of the French press character.
Core Parameters
| Parameter | Standard | Notes |
|---|---|---|
| Brew ratio | 1:15 | 30g coffee / 450g water for 3-cup press |
| Water temperature | 93–96°C | Just off boil; use boiling if no thermometer |
| Steep time | 4 minutes | From first pour to pressing |
| Grind size | 1000–1200 microns | Coarse; coarser than any filter method |
| Bloom | Optional | 30-second bloom recommended for fresh coffee |
| TDS (cup) | 1.1–1.35% | Slightly heavier than pour-over |
Immersion vs. Percolation
French press is an immersion method: coffee grounds are fully submerged in water for the entire steep time. Water doesn’t pass through the bed — it surrounds it. This has several consequences:
- Extraction rate decreases over time as the water becomes more saturated with dissolved compounds. The concentration gradient between grounds and liquid narrows, slowing further extraction.
- Extraction is more self-limiting than percolation methods. This is why French press is relatively forgiving of timing variations — an extra 30–60 seconds rarely ruins the cup.
- Because water contact is equal across all grounds simultaneously, French press rewards even grind distribution but is less sensitive to pouring technique than pour-over.
Percolation methods (V60, Chemex, pour-over) pass fresh, unsaturated water through the coffee bed continuously, maintaining a high concentration gradient throughout brewing. This extracts more efficiently per unit time but is more sensitive to channeling and pour consistency.
The Metal Filter: What It Retains
The French press plunger uses a metal mesh filter. Unlike paper filters, metal mesh:
- Retains coffee oils: Cafestol and kahweol, diterpene compounds found in coffee lipids, pass through the metal filter into the cup. Epidemiological research has linked these compounds to modest increases in LDL cholesterol with regular consumption of unfiltered coffee. Paper-filtered coffee removes the majority of these diterpenes.
- Retains micro-fines: Fine coffee particles — especially from burr grinder outputs — pass through the mesh and remain suspended in the cup, adding body, increasing TDS slightly, and producing sediment at the bottom.
- Produces a heavier mouthfeel: Retained oils coat the palate, creating the characteristic richness of French press that paper-filtered methods don’t replicate.
Filter Comparison: Body and Clarity
| Method | Filter type | Oils retained | Fines in cup | Body | Clarity |
|---|---|---|---|---|---|
| French press | Metal mesh | High (~100%) | Yes (sediment) | Very full | Low |
| AeroPress (metal) | Metal disc | High | Some | Full | Low-medium |
| AeroPress (paper) | Paper | Low | No | Medium | High |
| V60 | Paper | Low | No | Light-medium | High |
| Chemex | Thick paper | Very low | No | Light | Very high |
| Espresso | No filter | High | N/A (pressure) | Concentrated | N/A |
Pressing Technique
After 4 minutes of steeping, press the plunger slowly and steadily — 20–30 seconds to fully depress. Pressing too fast forces grounds through the mesh, increasing sediment and fine particles in the cup. Pressing too slow isn’t a problem.
Critical: Pour the coffee immediately after pressing. Leaving brewed coffee sitting on grounds (even pressed) continues extraction, producing bitterness over time. If you’re not serving immediately, pour all coffee into a separate carafe.
Bloom for French Press
A bloom step is optional for French press but beneficial for fresh coffee (roasted within 1–3 weeks). Pour 60–90g of water over 30g of grounds, stir gently to wet all grounds, and wait 30–45 seconds. Then add the remaining water and begin the 4-minute steep timer. This ensures even saturation of all grounds before full immersion, which improves extraction consistency.
For coffee older than 4–6 weeks, the bloom is largely unnecessary as CO₂ has already off-gassed.
Grind Size Matters More Than You Think
French press uses the coarsest grind of any common brewing method. At 1000–1200 microns, particles are large enough that:
- The metal mesh can block most of them during pressing
- Extraction at 4 minutes reaches an appropriate yield without over-extracting
A grind that is too fine for French press causes two problems: (1) grounds pass through the mesh into the cup, and (2) the finer grind extracts faster, often resulting in over-extraction at the standard 4-minute mark. A grind that is too coarse under-extracts — sour and thin despite full steep time.
James Hoffmann popularized an alternative technique using an extremely coarse grind (~1400 microns), a longer steep (8–12 minutes), and a gentle skim of foam before pressing — producing a cleaner cup with less sediment than traditional French press technique.