What Are the Differences Among So Many Pour-Over Coffee Drippers? What Are Ribs?

Understanding Dripper Construction: How Design Affects Coffee Extraction

In yesterday's article, FrontStreet Coffee mentioned that most people initially choose their drippers based on functionality. For example: "This dripper produces cleaner coffee," "This dripper creates fuller-bodied coffee," or "This dripper enhances the sweetness of the coffee."

These extraction characteristics revolve around the dripper's construction, and their differences create distinct extraction effects when certain structural elements are modified. Today, FrontStreet Coffee will provide a detailed analysis of how dripper construction impacts extraction!

The Function of Drippers

Regardless of their shape, all drippers serve two primary functions: flow guidance and drainage speed. These are reflected in the distribution of flow ribs and the size of drainage holes.

Flow Ribs

Flow ribs can be either raised lines on the dripper walls or base, or recessed grooves like those found in Ice Crystal or Cross Star drippers. These lines or grooves support the filter paper, creating gaps that we call "flow channels." Flow channels have one main purpose: to guide the direction of water flow and increase the space through which water can pass.

Without flow channels, a dripper would merely be a funnel supporting filter paper (like Melitta's original conical dripper design), where water could only percolate downward by gravity. Imagine a Kono without ribs or a Chemex coffeemaker where the filter paper completely adheres to the surface. The only space for water flow would be the small area around the bottom hole. This limited space, largely occupied by coffee grounds and potentially blocked by fine particles, would result in extremely slow water flow (the kind of slowness that leads to over-extraction!). Therefore, flow channels are needed to alter water's path and increase the drainage area.

Flow channel designs vary widely, with traditional vertical designs being common. Drippers like Kono and Origami employ this approach, using vertical ribs of varying lengths to support the filter paper and create space for water flow. The longer the ribs, the greater the space for rapid water drainage. Areas without ribs experience slower flow, causing the coffee grounds in those regions to undergo immersion-style extraction.

The V60 dripper's flow channels consist of spiral ribs of alternating lengths. These spiral ribs change what would be vertical percolation into spiral flow along the ribs, allowing hot water to flow quickly while ensuring even coffee extraction.

Some special drippers, like the Ice Crystal dripper featured in yesterday's article or the Cross Star Infinity dripper, have flow channels created by inward curvatures on the dripper walls. The purpose of these indentations is同样 to create gaps, providing more space for water flow.

Drainage Holes

After discussing flow channels, let's examine drainage holes. The size and number of these holes are crucial design elements that determine water flow speed. Their design must work in harmony with the flow channels—both are essential.

The world's first dripper, designed by Melitta, was a trapezoidal dripper with multiple ribs. Despite having numerous ribs, its single, very small hole resulted in extremely slow water flow, frequently causing over-extraction!

This created an opportunity for Kalita to "borrow" the design and introduce their trapezoidal three-hole dripper, significantly improving drainage speed! Therefore, the larger or more numerous the drainage holes, the more space available for water to pass through.

Therefore, not all drippers with flow channels drain as quickly as the V60. They need this design to control drainage speed within a reasonable timeframe, thus avoiding over-extraction!

Materials

Common dripper materials include resin, ceramic, metal, and glass. These have minimal impact on extraction, mainly differing in their thermal conductivity properties. However, without extensive preheating with hot water before brewing, these differences are negligible, at most providing some heat retention.

Conclusion

Once we understand the main design principles of drippers, we can roughly determine their differences based on appearance. This way, when purchasing, we won't be dazzled by the colorful variety of drippers. By the way! Many manufacturers have recently introduced valve-equipped drippers. These add adjustable, controllable drainage switches to conventional dripper designs. This feature not only significantly lowers the entry barrier for beginners but also provides experienced users with more versatility! After mastering conventional drippers, trying "smart dripper" versions can be an enjoyable diversion.

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