Coava Coffee Roasters, The Kone (K-ONE) Pour Over Filter

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Keith Gehrke humors me with an in-depth discussion about his soon-to-be-released metal pour over filter named the Kone. Known as the K-ONE in its earlier stages, the filter is based on the common Melitta paper filters used for most pour over brewing. Keith calls it a “selfish project” that he started on his kitchen table in November of 2009. He set out to create a sustainable pour over process that also produced a better cup of coffee.

His initially attempt was a reusable filter that mimicked the brew process of paper filters. After some kitchen-table theorizing he realized paper filters didn’t produce an ideal brew because the wet paper would hug the sides of the glass, restricting water flow to the tip of the filter and creating points of over- and under-extraction. Keith overcame this problem by redesigning the metal filter to taper quicker than the filter’s glass holder. The filter only touches the glass sides at its crown, at the very top of the Chemex holder. This holds the suspended filter away from the glass sides, allowing a free flow of water through the entire surface area of the filter and not just the tip.

The design is entirely custom, and the CAD drawings were drafted by a local engineer and submitted to a manufacturer on the East Coast. The stainless steel is sourced from Ohio and the filter’s holes are created by photochemical etching. The process creates a taper in the holes; the holes are bigger on the outside and smaller on the inside. This prevents clogging and makes cleaning easier. Only a few filters are cut from one sheet of steel, so Keith created several different versions of his design and ordered up a small test batches for each redesign.

Keith holds two filters up to the light. I can see that one allows more light through than the other. On closer inspection, one filter’s holes are closer together than the other. This is the difference between the 6th and 7th versions. Earlier versions featured a gradient of holes that were less dense at the top and denser at the bottom. The changes are made to control the speed that water exits the filter at any given location, brewing the grounds evenly and extracting all possible oils.

Matt and Keith have hit a good balance between the high acid light roasts that are currently in vogue around Portland and the darker roasts that appeal to the broader coffee drinker. It’s nice to see them experimenting with brewing technology and growing coffee plants. Their tasting room on Grand Ave is well worth the trip.

Tentative Release & Price: Late October 2010, $50