Why Espresso Is Different
Every other brew method relies on gravity or steep time to move water through coffee.
Espresso uses pressure — 9 bar, roughly nine times the weight of the atmosphere — to
force hot water through a densely packed puck of finely ground coffee in under thirty
seconds. That pressure changes everything.
Extraction is faster and more intense than any other method, which is why espresso
produces a concentrated 30–40g shot from just 18g of coffee, with flavour and body that
no pour-over can replicate. It also means the margin for error is small. A grind
adjustment of a single click — sometimes less than 10 microns — can swing a shot from
outstanding to undrinkable. That precision is what makes espresso both humbling and
endlessly satisfying to dial in.
The Variables
Grind
Finer than any other method — the grounds should look and feel like fine table salt or
flour. Grind is the primary dial for controlling extraction: finer grinds create more
resistance, slowing the flow and extending contact time. Coarser grinds do the opposite.
A quality burr grinder with consistent, uniform particle size is non-negotiable for
espresso. No blade grinder, no matter how expensive, produces the consistency the method
demands.
Dose & Yield (Ratio)
A standard double shot: 18g of coffee in, 36g of espresso out — a 1:2
ratio. This is the baseline most specialty cafés work from. The ratio governs how much
water passes through the puck:
Ristretto (1:1.5) — stops early at 27g out. Sweeter, more concentrated,
lower volume. The early fractions of a shot carry the most sweetness and the least
bitterness. A ristretto captures that window.
Normale (1:2) — the standard. Balanced extraction across acidity,
sweetness, and bitterness. The right starting point for any new coffee.
Lungo (1:3) — runs to 54g out. Larger volume, more bitter compounds
dissolved, less body relative to the water used. Can taste thin if the coffee isn't
suited to it.
Shot Time
The target is 25–30 seconds from the moment the pump starts. Shot time
is a symptom, not a setting — you fix it by adjusting the grind. Too fast (under 22s)
means the grind is too coarse; too slow (over 35s) means too fine. Once you're in the
window, you taste and decide whether to go coarser or finer for flavour, not timing.
Temperature
Aim for 90–94°C. Slightly lower than pour-over because pressure-driven
extraction is more aggressive — you need less temperature to achieve the same yield.
For lighter roasts, lean toward 93–94°C to help develop sweetness. For darker roasts,
90–92°C keeps bitterness in check.
How the Variables Interact
Grind, time, and ratio don't act independently — they compound. Grind coarser and the
shot runs faster, extracting less. Run it longer by using a higher ratio and you pull
more bitterness into the cup. The widget below maps how adjusting each variable shifts
the shot's flavor profile.
Notice that grind and time carry the most weight — together they account for 85% of the
extraction index in this model, which reflects reality. Ratio matters less for extraction
yield and more for concentration and volume. A ristretto isn't more extracted than a
normale; it just stops before the bitter late fractions arrive.
Pulling a Shot: Step by Step
What you need
Espresso machine · Burr grinder · Portafilter · Scale · Timer
Recipe (double shot)
Dose: 18g (fine grind)
Yield: 36g
Ratio: 1:2
Time: 27–30s
Temperature: 93°C
Method
1. Grind 18g directly into the portafilter basket.
2. Distribute evenly. Tap the sides to settle the grounds, then use a
distribution tool or WDT (Weiss Distribution Technique) to break up clumps and eliminate
air pockets. Uneven distribution causes channelling — water finds the path of least
resistance and rushes through, leaving the rest under-extracted.
3. Tamp with firm, level pressure. Around 15–20kg of force is the
standard guidance, but consistency matters more than exact force. A crooked tamp is worse
than a light one.
4. Flush the group head with 2–3 seconds of hot water to clear any
residue and stabilise the temperature.
5. Lock in the portafilter, place your cup on the scale, zero it, and
start both the shot and the timer simultaneously.
6. Stop at 36g. Note the time.
7. Taste immediately, while it's still hot. Espresso changes as it
cools — and not always for the better.
Dialing In
One variable at a time. The standard troubleshoot is straightforward:
Shot runs too fast, tastes sour and thin — grind finer. You're
under-extracting. The water is moving through the puck too quickly to dissolve the
sweetness and body.
Shot runs too slow, tastes bitter and harsh — grind coarser. You're
over-extracting. The water is spending too long in contact with the coffee and pulling
the late, unpleasant compounds.
Time is right but the shot is still off — check your distribution
and tamp for channelling. Then consider adjusting temperature (up for more sweetness
and acidity, down for less bitterness) or dose (up for more body, down for a cleaner
cup). If you've changed coffees, start the grind adjustment from scratch — even a
similar roast level from a different origin can require a meaningfully different setting.
A useful rule of thumb: the grind sets the time; the ratio sets the strength.
Keep one constant while adjusting the other.
Mirlo's Recommendations
We profile our coffees to pull well as a 1:2 double at 93°C with a 27–29 second
extraction. If you're dialing in for the first time, start with a medium or medium-dark
roast. Lighter coffees are more sensitive to temperature and grind uniformity — they
reward an established technique, but they'll punish a poorly distributed puck more
readily than a darker roast will.
Once you've locked in a recipe, write it down. Shot-to-shot consistency comes from
eliminating variables, not from guessing. The best espresso you pull will probably be
the tenth shot on a dialled-in recipe, not the one you stumbled into on day one.
Curious about how we develop the flavour before it reaches your machine?
Read about how we roast.