Puck Prep – WDT, Distribution and Tamping Done Right
An even puck is half the battle. Here is how to prepare it – without channeling.
Even with a perfect grind, the shot turns out uneven if the coffee is badly distributed in the basket. Water takes the path of least resistance – that is channeling. Clean puck prep prevents exactly that and makes your shots repeatable.
What is channeling?
Channeling means water breaks through a weak spot in the puck and runs concentrated there instead of evenly. The result: partly over-extracted (bitter), partly under-extracted (sour) – in the same shot. Visible as spritzing or pale jets at the spout.
Dosing and grooming
First dose evenly (ideally by weight). Break up clumps and roughly spread the coffee so there are no holes or mounds. A level, filled basket is the base for everything that follows.
WDT: Weiss Distribution Technique
Using a thin needle (or a WDT tool) you stir the dry grounds in the basket briefly. This breaks up clumps and evens out density – the single most effective step against channeling. Just a few seconds, big effect.
Distribution and tamping
A light polish (short twist) smooths the surface further.
- After WDT, level the surface (distributor or gentle tap).
- Tamp straight and centred – aim for a flat surface, not maximum force.
- Pressure is secondary; levelness is what counts. A tilted tamp means one-sided extraction.
The routine in short
Dose → break up clumps → WDT → level → tamp straight → pull. Always do it the same way: consistency in puck prep is what makes taste differences comparable.
Puck prep FAQ
Do I need a WDT tool?
Not strictly – a thin needle works too. But WDT is the most effective step against channeling and almost always worth it.
How hard should I tamp?
Less important than people think. A straight, level surface matters more. Moderate, even pressure is enough.
How do I spot channeling?
An uneven, spritzing pour, pale jets at the spout, and a shot that tastes sour and bitter at once.
Does puck prep help with bitter espresso?
Often yes. Uneven extraction from channeling creates bitterness – an even puck reduces it noticeably.
Clean puck, better shot
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