# Extraction Levers

Framework for understanding which variables change flavor, strength, extraction, and evenness.

## Contents
- Purpose
- Quick decision map
- Extraction vs strength vs evenness
- TDS and EY
- Ratio
- Flow
- Debit vs flow
- Pressure
- Temperature
- Water
- Roast
- Process and freshness
- Dose / basket / puck thickness
- Evenness
- Practical order of operations
- Family interactions
- Common mistakes
- Closing rule of thumb

## Purpose

Use this file when answering questions like:
- what does changing flow actually do?
- why did lower pressure help?
- is this a strength problem or an extraction problem?
- should the next move be grind, ratio, pressure, temperature, or water?

This file is the public theoretical backbone of Local.
It should stay general and publishable.

---

## Quick decision map

Use this section when the main uncertainty is not the symptom itself, but **which kind of problem this is** and **which lever class should move next**.

### 1. If the cup is mainly too weak or too intense
Think **strength** first.

Start with:
- **ratio** first,
- then **dose** if the beverage format is still wrong.

Do **not** start with pressure by default.

### 2. If the cup is mainly sharp, underdeveloped, or raw
Think **extraction** first.

Start with:
- **ratio**,
- then **grind**,
- then **temperature** or **family** if the basic structure is already reasonable.

Do **not** keep pushing finer if the cup becomes harsher or more unstable.

### 3. If the cup is sour and bitter together, confused, or structurally unstable
Think **evenness** first.

Start with:
- **puck prep**,
- **pressure / flow stress**,
- **family choice**,
- and sometimes **dose geometry**.

Do **not** assume this is a simple extraction problem.

### 4. If the shot technically works, but the expression is wrong
Think **family mismatch** first.

Start with:
- **family / flow-pressure style**,
- then fine-tune with ratio or temperature.

Do **not** assume the answer is just grind.

### 5. If nothing reasonable seems to land
Think **hidden variables**.

Check:
- **water**,
- **freshness**,
- **dose / basket geometry**,
- **thermal behavior**.

### Fast rule of thumb
- **Strength problem** → move **ratio** first.
- **Extraction problem** → move **ratio / grind** first.
- **Evenness problem** → reduce **stress** and improve **structure** first.
- **Family mismatch** → change **style**, not just resistance.
- **Hidden-variable problem** → check **water / freshness / geometry / heat**.

---

## Start by separating three different problems

Many espresso conversations get confused because people use the same words for different problems.
Before recommending a change, first ask which of these is most likely wrong:

### 1. Extraction
How much useful soluble material did we get out of the coffee, and how well did that extraction express the coffee?

Practical signals:
- sour, sharp, underdeveloped, or raw → often indicate insufficient extraction
- bitter, harsh, drying → often too much extraction or uneven extraction
- dull / muddy → can be too much blending, poor extraction structure, or water issues

### 2. Strength
How concentrated is the final beverage?

Practical signals:
- too weak, watery, tea-like → low strength
- too intense, syrupy, overwhelming → high strength

Strength is not the same thing as quality.
A coffee can be strong and badly extracted, or dilute and beautifully extracted.

### 3. Evenness
How uniformly was the puck extracted?

Practical signals:
- sour and bitter together
- sudden graph instability
- a shot that looks or tastes confused rather than simply “too much” or “too little”
- weirdly hollow cups that do not improve when you push extraction harder

A lot of bad espresso is not simply “under” or “over” extracted — it is **unevenly** extracted.

---

## TDS and EY: useful, but not magic

### TDS
TDS is the percentage of the final beverage that is dissolved coffee solids.
In practice, think of TDS mainly as a **strength** metric.

Higher TDS usually means:
- denser body
- more concentration
- more flavor intensity per sip

Lower TDS usually means:
- lighter body
- more dilution
- more openness, if the extraction is still good

### EY (Extraction Yield)
EY is an estimate of how much of the dry coffee mass was extracted into the cup.
In practice, think of EY as a rough **extraction** metric.

Higher EY is not automatically better.
Too high can taste:
- drying
- woody
- over-blended
- dull

Too low can taste:
- sharp
- underdeveloped
- thin
- incomplete

### Practical note
Taste still outranks the number.
A refractometer or estimated EY can be useful, but espresso flavor is more complicated than one number.

---

## Ratio is the easiest bridge between strength and extraction

Ratio is one of the most powerful and practical levers because it usually moves both strength and extraction in understandable ways.

### Shorter ratio
Often gives:
- higher strength
- more concentration
- more body
- less total extraction potential

Useful when the cup is:
- too diluted
- too bitter from excess extension
- better when compressed into a denser form

### Longer ratio
Often gives:
- lower strength
- more openness
- more extraction potential
- more clarity when the coffee can support it

Useful when the cup is:
- sharp / underdeveloped
- too intense or too narrow
- trapped in a short, dense format that is hiding sweetness

### Warning
Longer ratio is not a universal cure.
If the shot is already badly uneven, making it longer can just stretch the problem out.

---

## Flow: one of the most important flavor levers

Flow changes more than “how fast the shot runs.”
It changes contact dynamics, puck stress, and often flavor shape.

### In practical terms
Faster functional flow through the puck often tends toward:
- more clarity
- more front-loaded acidity
- less blending
- lighter texture

Slower functional flow often tends toward:
- more blending
- more body
- more integration
- sometimes more sweetness, but also more muddiness if pushed too far

### Why this matters
Two shots can have similar ratios and similar rough extraction outcomes, but taste very different because their flow regimes were different.

That is why flow is not just a speed variable.
It is a **flavor-shaping variable**.

### Useful mental model
- faster flow → more separation
- slower flow → more integration

Faster flow also often reduces contact time and may lower extraction unless other variables support it.
This is not a law, but it is a strong working heuristic.

---

## Debit vs flow: do not confuse them

These are related, but not identical.

### Debit
Debit is the water delivery rate available before the puck creates meaningful resistance.
Think of it as the machine-side fill rate.

### Flow
Flow, in the useful sensory sense, is the rate the brew is actually moving through and out of the puck.
This is what shapes the extraction character more directly.

### Why the distinction matters
A machine can be set to a high debit, but if the puck resists heavily, the actual shot behavior may still be slow and pressure-heavy.

Likewise, a lower-pressure profile can maintain a more open puck and deliver a faster effective flow through the bed even if the pump or inlet setting is not extreme.

This distinction becomes especially important in:
- profiling systems
- flow-control machines
- blooming profiles
- turbo / allongé families
- soup-style extractions

---

## Pressure: not a quality score

Pressure is often overvalued because it is visible and familiar.
But pressure is not “better” just because it is higher.
It is not an independent quality signal; it emerges from flow interacting with puck resistance.

### What higher pressure often does
- increases puck compression
- increases risk of channeling when the puck is already unstable
- can increase body and intensity
- can make the shot feel denser and more classical

### What lower pressure often does
- reduces puck stress
- can improve evenness
- can increase clarity
- may make the coffee easier to extract cleanly, especially when high pressure has been hurting it

### Good practical rule
If a coffee keeps turning harsh, jagged, or unstable, lowering pressure is often worth considering before assuming the answer is “just grind finer.”

### Another good rule
Pressure should be interpreted in context:
- 6 bar in a turbo-style shot can be perfectly healthy
- 6 bar in a traditional-style shot may or may not be enough depending on the goal
- very low pressure can be correct in soup or filter-style families

Do not judge pressure without the family context.

---

## Temperature: often smaller changes, big sensory effect

Temperature can dramatically change expression even when it does not create huge visible graph changes.

### Lower temperature often pushes toward
- softer acidity
- lower extraction intensity
- more muted or blended presentation
- less bitterness when a coffee is fragile or more developed

### Higher temperature often pushes toward
- higher extraction intensity
- more vivid acidity
- more aromatic definition
- higher risk of harshness if pushed too far

### Practical pattern
Especially for lighter coffees, temperature often feels like a bell curve:
- too low → muted, underexpressive, vague
- just right → clear, sweet, lively
- too high → bitter, sharp, or harsh

### Warning
Temperature is powerful, but it is not a replacement for fixing a broken flow / pressure / grind setup.
Do not use temperature to patch over a fundamentally bad shot structure unless you already know the structure is basically sound.

---

## Water: the hidden giant

Water is easy to ignore because it feels constant. Often it is not.

### Very simplified view
#### GH (general hardness)
Associated with calcium / magnesium content.
Rough practical effect: influences extraction behavior and body.

#### KH (carbonate hardness / alkalinity)
Acts as a buffer against acidity.
Rough practical effect: changes how sharp or muted acids feel.

### Water that is too soft can contribute to
- aggressive acidity
- “battery acid” sharpness
- unstable balance
- cups that seem impossible to round out

### Water that is too hard or too buffered can contribute to
- muted acidity
- flatter cups
- muddy or lifeless presentation
- loss of sparkle and separation

### Practical rule
If grind / ratio / temperature all seem reasonable and the coffee still refuses to land in a believable place, suspect water.

This is especially important for clarity-focused styles like:
- turbo
- allongé
- filter-style low-pressure
- soup

---

## Roast changes the whole system

Roast level changes what “good extraction” usually means.

### Lighter roasts
Usually:
- denser
- less soluble
- harder to extract cleanly
- more likely to reward longer ratios, better saturation, or lower-compression styles

They often benefit from:
- better wetting / soak strategy
- more extraction headroom
- clarity-preserving pressure and flow choices

### Darker roasts
Usually:
- more soluble
- easier to extract
- easier to overextract
- more likely to become bitter, ashy, or muddy under excessive pressure / contact time

They often benefit from:
- shorter ratios
- gentler extraction energy
- less aggressive pressure or temperature

### Important note
“High extraction” is not one universal target.
A beautiful medium-dark coffee may peak much earlier than a dense light roast.

---

## Process and freshness matter more than many people think

### Process
Washed, natural, honey, and experimental coffees do not all behave the same in the puck.

Very broad heuristics:
- washed coffees often behave more predictably
- naturals and experimental coffees can show more weirdness, more blending, or more puck instability
- some coffees want more saturation help before they want more pressure

### Freshness
Fresh coffee contains more CO2 and can disrupt extraction behavior.
This often shows up as:
- odd resistance changes
- erratic-looking bottomless flow
- confused sweetness / acidity balance
- shots that taste both sharp and messy

If a coffee is extremely fresh, a profile family with better wetting or blooming support may help more than simply changing grind.

---

## Dose, basket, and puck thickness

Dose is not just a yield anchor. It changes puck geometry.

### Higher dose / thicker puck
Can give:
- more body
- more concentration potential
- more resistance
- more difficulty achieving high and even extraction

### Lower dose / thinner puck
Can give:
- easier extraction
- better vertical evenness in some cases
- more ability to grind finer for a given flow outcome
- less body if pushed too far

### Important caution
Going too thin can create more radial evenness problems.
So this is not simply “lower is better.”

### Practical use
If a coffee stays stubbornly sour or underdeveloped even at long ratios and sensible temperature, slight downdosing can be a more intelligent move than endlessly chasing finer grind.

---

## Evenness: often the real bottleneck

A lot of dialing frustration comes from trying to solve an evenness problem with an extraction lever.

### Signs you may be fighting evenness, not simple extraction
- sour and bitter at the same time
- graph instability that does not match family intent
- finer grind makes the cup worse, but coarser grind makes it weak
- ratio changes move the cup around, but never really “solve” it

### Ways evenness can improve
- better puck prep
- better wetting / fill / soak design
- lower pressure
- faster, more open flow families
- dose change
- basket / filter changes

### Important principle
Sometimes the path to higher usable extraction is **not** “extract harder.”
It is “extract more evenly.”

---

## A practical order of operations

When taste is off and you are not sure what to change, a good reasoning order is:

1. **Identify the intended family**  
   Traditional? Blooming? Turbo? Soup? Filter-style?

2. **Decide whether the problem is mostly**  
   extraction, strength, or evenness.

3. **Use the simplest lever first**  
   Often ratio or grind.

4. **If the cup is structurally wrong, change the family or pressure/flow behavior**  
   Not every coffee wants the same extraction style.

5. **If nothing makes sense, check hidden variables**  
   water, freshness, dose, basket, thermal behavior.

---

## Family interactions: why this file matters to the taxonomy

These levers are not isolated from profile families.
They are the reason families taste different.

### Examples
- **Traditional** families usually lean more on concentration, body, and pressure stability.
- **Blooming** families often trade time and structure for better saturation and extraction depth.
- **Lever-like** families often shape sweetness and texture through declining pressure.
- **Turbo / allongé** families push clarity by lowering pressure and increasing functional flow.
- **Soup** pushes this logic even further with ultra-low pressure and a very open puck.
- **Filter-style low-pressure** trades espresso density for transparency and articulation.

That is why the same coffee can feel completely different under different families even when all are “technically” extracted.

---

## Common mistakes when using extraction levers

### 1. Treating time as the main target
Time is a clue, not the final objective.

### 2. Using pressure as a quality badge
More pressure is not more skill.

### 3. Confusing stronger with better
High TDS can still taste bad.

### 4. Confusing lower pressure with underextraction
In some families, lower pressure is exactly the point.

### 5. Fixing an evenness problem with more force
If the puck is unstable, more grind restriction or more pressure can make things worse.

### 6. Ignoring water
A lot of “mystery acidity” or “mystery flatness” is not mysterious at all once water enters the conversation.

---

## Closing rule of thumb

When in doubt:
- use **ratio** to move balance and strength,
- use **grind** to move extraction potential and resistance,
- use **flow / pressure** to shape expression and evenness,
- use **temperature** to fine-tune expression,
- use **water** when nothing reasonable is landing,
- and always ask whether the shot is using the right **family** in the first place.
