## Extraction Uniformity and Channeling

For a while now I’ve been trying to understand the details of channeling in pour over coffee, and I found it very difficult to find a convincing description of why channeling (and thus astringency) happens suddenly when we grind a bit too fine, even if the surface of the coffee bed looks flat at the …

## Why do Percolation and Immersion Coffee Taste so Different ?

In this post, I discuss the physics of extraction by percolation and immersion and how they lead to very different taste profiles.

## The Repeatability of Manual V60 Pour Overs

Today I decided to measure how repeatable and consistent my manual V60 pour overs are. My expectations were very low, given how variable an average extraction yield I often get when I brew the same coffee a few days apart. To do this, I used some older coffee I had left from a local roaster …

## A Recipe to Brew High Extraction Coffee with the Siphon

Today I am finally sharing a recipe for the siphon brewer. I will use a bit of technical jargon at times in this blog post. If you encounter a word you're not familiar with, I recommend you consult Mitch Hale's glossary. The siphon method is far from being appropriate for most people's daily routines, as …

## Testing a Model of Extraction Dynamics

In a recent post, I presented a mathematical model for the dynamics of coffee extraction that is based on a few simple hypotheses. One of these is that the rate of extraction decreases exponentially. The rate at which it decreases can depend on many things: the type of coffee, the roast, the amount of agitation …

## A More Accurate Way to Calculate Average Extraction Yield

I recently wrote about the detailed explanations and calculations behind the equations we use to estimate average extraction yield from coffee concentration (often called TDS) measured with refractometers. If you have not seen this discussion, I highly recommend reading it before you start reading this blog post, as it introduces a lot of the concepts …

## Measuring and Reporting Extraction Yield

Since I received the VST Coffee Lab III refractometer thanks to Vince Fedele's generosity, I started logging the concentration (in % TDS) of every coffee I brew. This allows you to calculate the average extraction yield of your brew, which represents the fraction of your coffee beans by mass that was dissolved in your brew …