How we measured espresso shower screen water distribution, and improved it
One of the biggest challenges in espresso extraction is ensuring the coffee puck is evenly saturated right from the start.
Most traditional shower screens, including the IMS CI200, tend to channel water into just a few narrow streams. This uneven distribution leads to patchy pre-infusion and can increase the risk of channeling, resulting in inconsistent shots.
To address this, we developed a new shower screen featuring carefully placed dimples that create multiple droplets across the entire surface. Our goal is to achieve uniform puck wetting at the earliest stage of extraction.
Enter the Dimples
Our new screen introduces “dimples” that serve as low points, guiding water droplets evenly across the entire surface.
To quantify this improvement, decent tester Mikelipino built a test rig called the “Flowtafilter” (3D printable by anyone).
His “Flowtafilter” device collects water in concentric rings labeled A, B, C, and D. Each ring has an equal surface area, so in a perfectly even scenario, each should receive about 25% of the total flow.
Water from even concentric section drains to separate vessels, which are then separately weighed.
In practice, “D” (the outermost ring) typically receives less water because the screen diameter is smaller than the basket.
To compensate, we've intentionally assigned more holes—or dimples—to ring “C,” effectively “overfilling” it. By nudging more water outward, the overall distribution remains far more balanced than what we see with a standard IMS CI200 screen.
The Test Results
Data from our Mike showed a dramatic reduction in variance when using our new dimpled design.
Even at low flow rates (such as 4 mL/s or below), the water spread is significantly more uniform compared to the IMS screen. At higher flow rates, the distribution remains stable, without forming jets or channels that concentrate in one area.
This means you can ramp up pressure for a fast pre-infusion or maintain a gentle trickle for a Slayer-style shot, and in both cases the screen delivers excellent coverage.
Why two designs?
In our testing we found both were good at different things:
• Freckles : This design features a high density of holes—over 1,000.
The advantage is redundancy: if some holes become blocked, the overall distribution remains largely unaffected. We suggest you use this for espresso.
• Dimples: In contrast, this design employs a more controlled approach, with each dimple containing just 7 holes (for a total of 420 holes).
This configuration is engineered to deliver optimal distribution under ideal conditions. We suggest you use this for filter.
Conclusion
By carefully engineering where and how water exits the shower screen, we've taken a significant step toward achieving a more predictable and balanced espresso extraction.
Our new design not only addresses the shortcomings of flat, hole-based screens but also avoids the pitfalls of overly simplistic approaches that can lead to blockage.
Whether you prefer the precision of Dimples or the redundancy of Freckles, our innovations ensure that every particle of coffee is evenly infused, paving the way for a consistently delicious shot every time.
#showerscreen #improvements #R&D
Updated 2025/02/21