Coffee: Dialing, Extraction, and Technique
Troubleshoot extraction flaws, master puck and bed physics, and engineer your water chemistry. Designed for experienced brewers looking to eliminate guesswork and achieve repeatable cup perfection.
Like Duolingo, but for Coffee: Dialing, Extraction, and Technique. Tomo turns the whole topic into a game you play five minutes a day, until it actually sticks.
24 levels across 4 sections, about 48 minutes end to end, roughly 10 days at five minutes a day. It moves through Diagnosing and Correcting Extraction, Percolation and Immersion Bed Dynamics, Chemical and Physical Variables, and Dynamic Extraction Control.
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Key ideas in Coffee: Dialing, Extraction, and Technique
- Astringency and harsh polyphenols wash out when water cuts high-velocity preferential paths through the bed
- A fast total brew time can still yield astringency if flow is uneven, because localized areas undergo extreme over-extraction
- Uniform long contact time increases general extraction yield, but true astringent dryness specifically indicates flow channeling
- The sour-bitter paradox occurs when severe channels over-extract narrow pathways while leaving the surrounding dense coffee dry and under-extracted
- Coarsening or redistributing to fix uneven bed resistance resolves this mixed defect, rather than trying to balance the two flavors in the middle
- A uniform extraction never produces simultaneous extremes of grassy under-extraction and bitter over-extraction
- Brew ratio establishes the solute-to-solvent balance, determining strength (TDS) and maximum possible extraction yield
- Grind setting directly dictates exposed surface area and the rate at which soluble compounds enter solution
- Adjusting ratio cannot fix clarity or velocity issues caused by improper particle surface area
- Increasing the dry coffee dose increases physical bed depth and hydraulic resistance, extending contact time
- Adding dose reduces the headspace between the coffee puck and the shower screen, altering pre-infusion saturation dynamics
- Changing dose preserves the identical unimodal or bimodal grind particle distribution produced by the burr setting
- Locking dose first fixes headspace and basket geometry as static baselines
- Selecting and fixing a target beverage yield locks in the baseline brew ratio
- Adjusting grind size as the final isolated variable tunes flow velocity, contact time, and flavor clarity to taste
- Dry internal clumps resist compression differently than loose grounds, creating localized horizontal density variations
You've tried the other tabs
Thirty open tabs. Four facts you actually kept.
You watched. You nodded. By Sunday it was gone.
One answer, then back to scrolling.
Eight weeks. You meant to finish. You didn't.
Tomo gives Coffee: Dialing, Extraction, and Technique the Duolingo treatment: levels, streaks, and quick quizzes that test what you just learned. That game loop is what the tabs above never had, so it's the one you actually finish.
Here's what playing it feels like
A real question from this course. Take your best guess.
Your pour-over tastes unusually parching and chalky. What physical mechanism causes this harsh astringency?
Get it right to open this lesson and 23 more in the app.
Where Coffee: Dialing, Extraction, and Technique takes you
- 1
Diagnosing and Correcting Extraction
- Calibrating Flavor and Flow
- Espresso Puck Preparation Mechanics
- 2
Percolation and Immersion Bed Dynamics
- Percolation Fluid Dynamics and Geometry
- Immersion and Hybrid Contact Control
- 3
Chemical and Physical Variables
- Water Chemistry and Buffer Engineering
- Burr Alignment, Geometry, and Grind Distribution
- 4
Dynamic Extraction Control
- Pressure and Flow Profiling
- Thermal Profiling and Yield Targets
4 sections · 8 units · 24 levels. Built to play, not to enroll.
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You pick the voice
Coffee: Dialing, Extraction, and Technique is taught in the The Professor style: clear, structured, thorough. Want a different feel? In the app you can spin up the same topic in any of Tomo's teaching styles. Same facts, totally different vibe.
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Dialing In Espresso
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