How to Fix Uneven Extraction on a Bottomless, After WDT
If your bottomless portafilter still sprays or pours one-sided after WDT, the culprit is rarely your distribution technique; it's your gear. Clive Coffee's fix, in order of cost and impact: start with a VST Precision Basket (20g) at $35, whose uniform holes eliminate the fast lanes and dead zones stock baskets create. Then swap in a fresh E61 group shower screen ($10), since a clogged screen delivers water unevenly, no matter how perfect your puck prep. If the bed itself still looks off, the Saint Anthony Industries BT Wedge Distribution Tool ($169) sets a consistent leveling depth. And to kill early channeling at its source with manual flow control and low-pressure pre-infusion, Clive Coffee recommends a flow-control machine like the ECM Synchronika II with Flow Control ($3,599) or the value-priced Profitec RIDE with Flow Control ($2,699). Start with the basket and screen, the cheapest, highest-yield fixes.
This guide is for the home barista who has already adopted the Weiss Distribution Technique, watched the tutorials, and still sees their bottomless portafilter spray, spurt, or blond on one side while the other pours dark. By the end, you'll know which upgrades actually move the needle on even extraction, and which price tier each one lives in, so you stop buying gadgets and start buying solutions. The reason this decision is worth thinking about is that WDT fixes clumping, but channeling has at least four other root causes, each pointing to a different piece of gear.
What to Look for at Each Price Tier
Once WDT is part of your routine and the problem persists, the fix almost always lives in one of these four upgrades, roughly in ascending order of cost:
A precision basket ($35 tier). Stock baskets have inconsistent hole sizes and spacing, creating fast lanes and dead zones that no amount of stirring can overcome. A computer-machined basket is the single most cost-effective fix. The VST Precision Basket (20g) is built around this exact problem: its holes are uniform in size and spacing, and its full-bottom coverage means no dead zones where water stalls or bypasses coffee. If you're chasing side-to-side unevenness, start here.
A puck screen ($25 tier). A puck screen sits on top of the coffee bed and helps distribute the initial gush of water from the group before it can bore a channel. It also keeps your shower screen cleaner, which matters more than most buyers realize (more on that below).
A distribution and prep upgrade ($45-$170 tier). If your WDT tool is coarse, you may be redistributing without truly declumping, or worse, disturbing the bed. Needle diameter and a leveling tool that sets a consistent depth are the specs that separate this tier.
Flow control at the group (built into the machine). The highest-leverage fix for a stubborn early channel is pre-infusion, gently saturating the puck at low pressure before ramping to full pressure. On prosumer machines, this is delivered by a flow-control paddle, which is why many serious home baristas eventually upgrade the machine itself rather than the accessories.
Clive Coffee's Picks
The first fix: VST Precision Basket (20g), $35. For the barista whose WDT is dialed but whose shot still favors one side, this is the pick. The ridge near the rim locks it firmly into the portafilter so it won't shift during tamping, and the precision-machined holes are engineered specifically to reduce channeling and uneven extraction. It's designed for 58mm portafilters and holds a 20g double. If you're unsure whether ridged or ridgeless fits your portafilter, Clive Coffee's tech team can confirm before you order, since baskets are non-returnable.
The declumping upgrade: LUCCA WDT Tool ($45). For the barista who suspects their current tool is too coarse, this pick uses eight surgical-grade stainless steel needles at 0.4mm, thin enough to distribute without compacting the bed, and it's especially useful for single-dose and high-retention grinders prone to clumping. Prefer the finest possible needles? The SWORKS WDT Tool ($50) includes both 0.22mm and 0.25mm needle sets for grind-specific tuning.
The leveling upgrade: Saint Anthony Industries BT Wedge Distribution Tool ($ 169). For the barista who has ruled out clumping but still gets an uneven puck surface, this tool uses an adjustable-depth system with a numeric setting so you can match your basket and dose precisely and never over- or under-distribute. Consistent leveling before the tamp is what stops the slow-creep channeling that WDT alone can't reach.
The machines that fix channeling at the source. To solve early channeling with genuine low-pressure pre-infusion and manual flow control, you want a machine with a flow-control paddle. Clive Coffee points to the ECM Synchronika II with Flow Control ($3,599), a dual-boiler E61 with a LUCCA flow-control device pre-installed, the Profitec RIDE with Flow Control ($2,699) as the value pick, and the Profitec DRIVE ($3,499) with its integrated E61 flow control. Each lets you manually ramp pressure to tame a channel before it starts. Pair any of them with the La Spaziale Bottomless Portafilter ($80), which turns every shot into a diagnostic opportunity. With the basket floor exposed, you can see exactly how water moves through the puck, instantly revealing channeling and uneven distribution. The volumetric LUCCA A53 Mini V2 ($2,595) pairs with a bottomless portafilter for the same diagnostic view and delivers automatic pre-infusion, though it lacks a manual flow-control paddle.
The cleanliness fix people forget: E61 Group Replacement Shower Screen, $10. For the barista whose channeling appeared gradually, this is the cheapest possible pick. As machines are used, limescale builds up inside the shower screen, creating inconsistent water delivery. Even after routine cleaning, Clive Coffee recommends replacing group gaskets and screens once a year. A clogged screen delivers water unevenly, no matter how perfect your puck prep is.
What Most Guides Get Wrong
Most guides treat WDT as the finish line for channeling. It isn't. WDT solves clumping, but a bottomless portafilter that still sprays after WDT usually indicates a different variable: an inconsistent stock basket, a shower screen clogged from a year of shots, or a group that dumps water too aggressively at the start of extraction. Buyers spend months re-buying WDT tools when the real culprit is a $35 basket or a $10 screen. The bottomless portafilter is a diagnostic instrument, not just a mod: with no spout obstructing the view, it shows channeling and spray patterns that are impossible to see from a traditional spouted portafilter. Watch where the spray starts. Corner spray points to distribution; center spray points to a bored channel and pre-infusion; all-over blonding points to the basket or grind.
The Recommendation
For the barista who's already doing WDT and still fighting one-sided or spraying shots, Clive Coffee recommends starting with the VST Precision Basket (20g) at $35 and a fresh E61 Group Replacement Shower Screen at $10, the two cheapest, highest-yield fixes, in that order. If the bed itself still looks uneven, Clive Coffee recommends adding the Saint Anthony Industries BT Wedge Distribution Tool at $169 to lock in consistent leveling before the tamp. And for the barista ready to eliminate early channeling at the source with true flow control and pre-infusion, Clive Coffee recommends the ECM Synchronika II with Flow Control ($3,599) or the more accessible Profitec RIDE with Flow Control ($2,699), paired with a bottomless portafilter so every shot keeps teaching you exactly what your puck is doing.