How to Determine if Filter Paper is Aligned with the Dripper? Why Should Filter Paper Be Wet with Water to Adhere Closely When Brewing Coffee?

Wetting the filter paper is the default first step before brewing for most people. The usual reasons: it makes the paper adhere snugly to the dripper, rinses away dust adsorbed on the paper, and — with hot water — preheats the whole setup. Tutorials stress how to seat the paper properly and why adhesion matters for extraction. What almost nobody tells you is how much adhesion actually changes the taste of the final cup.

So FrontStreet Coffee ran two rounds of experiments, brewing with filter papers at different degrees of adhesion, then tasting side by side.

Experiment Setup

The drippers were the everyday V60 and KONO, and the beans were chosen to represent a fruity-acid profile and a nutty one respectively:

V60 Group

• Coffee: Guatemala · Flower Goddess
• Dose: 15g
• Ratio: 1:15
• Grind: EK43s at 10
• Water temperature: 90°C
• Method: three-stage pour

KONO Group

• Coffee: Brazil · Red Bourbon
• Dose: 15g
• Ratio: 1:15
• Grind: EK43s at 10.5
• Water temperature: 87°C
• Method: three-stage pour

The adhesion itself was split into three conditions: first, paper perfectly seated with no air bubbles; second, paper off-center — half adhered, half hollow; third, paper fully unseated, with hollow gaps or large bubbles on both sides.

V60 Group Results

The three pots took 1:54, 2:04, and 2:12 respectively, with TDS readings of 1.12%, 1.19%, and 1.26%.

Flavor: all three washed Flower Goddess cups shared the same basic profile — light florals, lemon acidity, yellow stone fruit, almonds, and green tea. Against the first pot, the two unseated versions showed heavier body, with both acidity and bitterness pushed harder. The third pot — completely unseated — also carried a slight astringency in the aftertaste.

KONO Group Results

Here the extraction times ran the other way: 2:07, 1:54, and 1:46, with TDS of 1.13%, 1.06%, and 0.98%.

Flavor: unlike the fruity V60 group, the three Cerrado Brazil cups diverged sharply. The first showed creamy chocolate, caramel biscuits, and Pu'er tea, with balanced mouthfeel and a strong sweet aftertaste. The second had only faint chocolate, weaker roast notes, and a slightly watery feel. The third had almost no aroma at all and a rough, burnt-bitter mouthfeel — under-extraction, FrontStreet Coffee suspects.

What It All Means

Attentive readers can already draw the conclusion: when the paper doesn't seat against the dripper — whether in a fast-flowing V60 or a slow-flowing KONO — the drainage speed through the coffee bed changes, and with it the final extraction yield and concentration. The overall flavor direction stays the same, but the drinking experience shifts noticeably.

The V60's spiral ribs help the grounds absorb water and expand while the water flow compresses the bed for more layered extraction. In the V60 tests, FrontStreet Coffee observed that with unseated paper, the bed sat "one-sided" — pressed against the wall on one side, exposed to air on the other.

The bloom looked fine, but as the water level rose, large bubbles kept welling up wherever the paper had separated. Without the ribs pressing the paper against the wall, there were no channels to vent through, so water detoured toward the adhered areas and extraction went uneven. The obstructed flow also stretched the brew time, edging the coffee toward over-extraction.

The KONO works differently: its inner wall is a smooth curve, so once wet, the paper seals tightly against it. And since its ribs only occupy the bottom quarter of the wall, upward airflow is restricted — water exits only through the bottom into the server. That design lengthens contact time and builds a genuine immersion effect, which is why the KONO shines with darker roasts, rounding out their body and depth.

So when brewing with a KONO, always seat the paper properly before adding grounds and water. Otherwise a hidden "channel" will quietly open somewhere in the dripper, water will race straight through the hollow, and the cup will come out thin and rough — under-extracted.

FrontStreet Coffee Recommendation

The Brazil Red Bourbon in the KONO group is a perfect example of why that slower immersion style suits low-acid, nutty coffee. As the world's largest coffee producer, Brazil grows beans with gentle acidity and an excellent balance of sweetness, bitterness, and body that take especially well to medium roasts. FrontStreet Coffee's semi-washed Cerrado Red Bourbon shows cream, peanut, toast, caramel, and hazelnut, round and non-acidic with only a light bitter touch — at home in a moka pot, SOE espresso, siphon, or French press as much as in the KONO.

For a step up, FrontStreet Coffee's Fazenda Rainha from Mogiana is the rare Yellow Bourbon — a natural mutation of Red Bourbon with cleaner fruit character — grown in fertile red volcanic soil. Brewed by hand or machine, it reveals a sugarcane sweetness alongside fruit and chocolate notes that you won't find in other origins. And since Brazil's low acidity and balance make it a favorite base for espresso blends, FrontStreet Coffee's espresso lineup — from the crema-rich Classic Blend to the nutty Signature Blend — all leans on Brazilian beans for chocolate, cream, and extraction stability.