Puck Prep

Puck prep is everything you do between grinding and pulling the shot. Its goal is a uniform bed of coffee that offers the water even resistance everywhere, so the shot flows evenly instead of carving a channel through the weakest point. Channeling ruins a shot that no amount of dialing in can rescue. The order of steps matters, because each one depends on the last — you cannot break up clumps after tamping, and you cannot level a tilt once the puck is compressed.

The order

Grind → WDT → distribute → tamp → (optional puck screen) → brew

The numbered steps

1. Grind into the basket or a dosing cup. Grinding straight into a dosing cup keeps things clean and gives you a contained space to work the grounds before they go in the basket.
2. WDT — the single most effective anti-channeling step. Stir the dry grounds with the fine needles of a WDT tool to break up static-bound clumps and even out the density of the bed. Move in small circles all the way down to the basket floor, not just across the top. Modern grinders throw clumps that trap air and create weak spots; this stir eliminates them. Do this before you level or tamp — you cannot fix clumps later.
3. Distribute and level the surface. Tap the basket gently or run a distributor across the top so the grounds sit flat and even, with no mound or dip. A level surface going into the tamp gives a level puck coming out.
4. Tamp — level beats forceful. On a flat surface, keep your wrist straight and elbow at roughly 90 degrees, and press straight down with steady, repeatable pressure. Level matters far more than how hard you push: a tilted tamp leaves one side of the puck thinner, and water escapes through that thin edge. Find a pressure you can repeat every shot rather than chasing a number of pounds. Use a tamper matched to your basket — the 58mm tamper fits standard portafilters snugly, leaving no untamped ring at the wall.
5. Optional: add a puck screen. Place a puck screen on top of the tamped bed. It keeps the shower screen cleaner and helps even out the initial flow of water into the puck. It is a refinement, not a substitute for good WDT and a level tamp.
6. Wipe the rim and lock in gently. Brush stray grounds off the basket rim so the portafilter seats cleanly, then lock it into the group without banging it. A knock can crack the puck and cause channeling — the very thing you just worked to prevent.
7. Verify with a bottomless portafilter. Watch the underside as the shot pulls through a bottomless portafilter. A single, even, mirror-like stream that merges to the center means your prep worked. Spraying, squirting, or jets shooting sideways mean channeling — go back and revisit your WDT and tamp.

Order summary

Grind → WDT → distribute → tamp → (screen) → brew. Get the sequence right and the bed does the rest. For a full symptom guide, see troubleshooting.