Water flow & agitation
Every pour is a stir — 5 min
Agitation is any movement of water relative to grounds — and every pour is agitation, whether you meant it or not. Around each coffee particle, the water closest to the surface saturates with dissolved coffee within seconds, and extraction through that tired layer slows to a crawl. Movement sweeps the layer away and puts fresh water back against the particle. That is the entire mechanism: agitation does not create extraction, it un-pauses it.
Which means your kettle is a stirring device. Pour height, flow rate, and where the stream lands all change how much energy enters the bed — a high, fast pour churns the slurry; a low, slow spiral barely disturbs it.
In the app
The rest of this lesson is in the Blend app — with the interactive widget and the practical brew.
Finish this lesson in the app.
The interactive widget, the footnotes, and the practical brew you can taste. Free on iOS and Android.