Coffee Data Science

Studying Coffee Migration Through Experimentation

Pushing the limits of espresso knowledge

Robert McKeon Aloe
Geek Culture


I wanted to better understand how coffee grounds move around larger boulders. So I made the experiment larger using whole beans and spent grounds.

While the smaller particles moved through the spacing between the beans, they moved slower and eventually clogged up.

A fun experiment using whole beans and spent grounds to look at how erosion occurs in the puck.

I repeated my whole bean and spent coffee experiments with my DE. As expected, the coffee grounds filled the gaps, but they didn’t come out into the cup more than 0.01g.

I looked at how coffee migrates, and I thought about what would have to happen to cause fines to migrate much more than the small percentage of fines that move.

With some agitation, I was able to get a lot of particles into the cup.

I did another experiment on forced fines migration with chalk. This showed chalk was forced out into the cup like the coffee fines were which helps validates my original chalk fines migration experiment.

The original criticism was that chalk doesn’t behave like coffee fines, but this experiment shows that chalk behaves similarly.

Measuring fines in coffee, let alone defining them, is challenging. For fines smaller than 50um in diameter, they are difficult to image.

So there’s always this question of how many fines are actually present if they are difficult to measure.

I figured out I could use wet sifting using a Kompresso so I did some experiments measuring fines. The results don’t contradict previous measurements on particle distributions throughout the puck.

In espresso, we talk about some fines making it into the cup, but it isn’t quantified.

So I did an experiment to measure how many fines end up in the cup after an espresso shot based on some techniques I had used to understand forced fines migration.

I’ve been really interested in the Osma espresso shot and how it works.

I was concerned that the vibration would cause finer particles to migrate in a more significant way than in regular espresso, so Hiver and I pulled a few shots and did some tests to explore.

I adjusted one of my experimental variables in espresso to better match what academic literature says about fines migration in soil.

Voila! Fines migrate a lot!

Slight variations in espresso variables have a big impact.

If you like, follow me on Twitter, YouTube, and Instagram where I post videos of espresso shots on different machines and espresso related stuff. You can also find me on LinkedIn. You can also follow me on Medium and Subscribe.

Further readings of mine:

My Future Book

My Links

Collection of Espresso Articles

A Collection of Work and School Stories



Robert McKeon Aloe
Geek Culture

I’m in love with my Wife, my Kids, Espresso, Data Science, tomatoes, cooking, engineering, talking, family, Paris, and Italy, not necessarily in that order.