Ren龙 / notes / coffee @renman

field note · 6 min read · 4 methods · 2 calculators

“Perfect” isn't a recipe — it's a handful of variables you learn to control. Master the levers and any bean, any gear gets better. No espresso machine required.

the one idea

Taste is extraction

Coffee is ~98% water dissolving flavour out of the grounds. Dissolve too little and the cup is sour and thin (under-extracted). Dissolve too much and it's bitter and harsh (over-extracted). The sweet spot sits between.

Everything below is just a way to push extraction up or down. Learn to taste which way you missed, and you can fix any cup.

the levers · ranked

Six variables that decide the cup

  1. Fresh beans. Whole, roasted weeks ago — not months. The biggest quality gate. Pre-ground stales within hours; beans peak around 4–21 days off roast.
  2. Grind. The most powerful daily lever. Finer means more extraction (and slower flow); coarser, less. A burr grinder — even a cheap hand one — beats any blade grinder, which hacks beans into uneven dust.
  3. Ratio. How strong. The filter standard is ~60 g coffee per 1 L water — that's 1:16–1:17. There's a calculator below.
  4. Water. 90–96 °C, just off the boil. And literally 98% of the cup: use clean, medium-mineral water — not distilled, not very hard tap water.
  5. Time & technique. How long water stays in contact with the grounds, and how evenly it wets them. Each method below sets its own time.
  6. Freshness of the pour. Grind right before you brew and drink within minutes — aroma escapes faster than you'd think.
interactive · ratio

Dial in your ratio

1 ml water ≈ 1 g
16 gcoffee ≈ 3 level tbsp · 250 ml water
at home · no espresso machine

Four methods for any kitchen

start here

French press immersion

The most forgiving: grounds simply steep in water. Minimal gear, hard to ruin.

grind
coarse
ratio
1:15–1:16
time
4 min, then press
enthusiast pick

Pour-over / V60 percolation

The most control and the cleanest cup. Water passes through the bed — you steer the taste with the pour.

grind
medium-fine
ratio
1:16–1:17
time
2:30–3:00 + 30–45 s bloom

Moka pot stovetop

Strong, espresso-adjacent. Water below the valve, don't tamp the coffee, low heat; pull it off when it gurgles.

grind
fine-medium
ratio
strong
time
~5 min on heat

AeroPress immersion

Fast, forgiving, portable. Great for a single cup; almost impossible to over-extract.

grind
medium-fine
ratio
1:14–1:16
time
1–2 min
interactive · troubleshooting

Diagnose your cup

change one variable at a time
Pick what's off about the taste — I'll show what to change.
what to skip

Five common mistakes

  • A blade grinder or pre-ground coffee. Uneven grind = sour and bitter at once.
  • Full-boil water on the grounds. Too hot pulls out bitterness. Let the kettle rest ~30 seconds.
  • Guessing amounts. Weigh coffee and water on a scale — otherwise you can't repeat a good cup.
  • Dirty gear. Old oils go rancid and add a stale note. Rinse after every brew.
  • Storing beans in the fridge or in sunlight. Moisture and light are the enemies. Airtight, room temperature, dark.