The Puck-Prep Playbook: Distribution & Tamping
The two seconds that decide whether your shot tastes like a café or a compromise.
Good beans, a dialed-in grinder, a machine up to temperature — and the shot still runs sour, uneven, and thin. Usually the problem isn't your coffee or your machine. It's the two seconds between grinding and brewing: how you distribute and tamp the grounds. Get this right and every shot becomes repeatable.
Why puck prep matters
Water takes the path of least resistance. If the bed of grounds is uneven — clumpy, tilted, or full of air pockets — water races through the weak spots and barely touches the rest. That's channeling: it over-extracts what the water rushes past (bitter) and under-extracts everything else (sour), often in the same cup. The fix is a uniform, level bed, so water meets equal resistance everywhere.
What you actually need
Three tools do the heavy lifting: a precision basket, a distribution (WDT) tool to break up clumps, and a calibrated tamper matched to your basket — 58mm for most prosumer machines, 54mm for the Sage/Breville Barista Express, 51mm for compact machines.
The four steps
- Dose — weigh it, every time (say, 18g). Consistency here makes everything downstream repeatable.
- Distribute — stir through the grounds with a WDT tool until even and clump-free. This single step kills most channeling.
- Tamp level — press straight down. Level matters far more than hard; a calibrated tamper clicks at a set pressure, so it's identical every time.
- Check & brew — the surface should be flat and smooth. Wipe the rim, lock in, and pull without delay.
The mistakes that cause channeling
Skipping distribution. Tamping a clumpy pile just locks the unevenness in place.
Tamping at an angle. Even a slight tilt sends water straight down the shallow side.
Tapping the puck after tamping. It cracks the compressed bed and opens fresh channels.
Read your shot
Once your prep is solid, the shot tells the truth about your grind. Fast, pale, and sour → grind finer. Slow, dark, and bitter → grind coarser. One side sprays while the other drips → that's channeling, so go back to distribution and a level tamp, not the grinder.
Coffee done well
Those thirty seconds of puck prep are where craft meets chemistry — invisible on their own, unmistakable in their absence. Precise, purpose-built tools take out the guesswork, so every shot is il caffè fatto bene.