What is Particle Size?
You’ve probably heard us go on ad nauseam (we won’t stop, by the way) about how crucial a good grinder is for making exceptional coffee. And when we get going on the importance of grinder choice, it won’t be long before the term particle size is uttered.
The consistency and size of your coffee grounds have a massive impact on the quality of your espresso. However, there are two significant hurdles to explaining just how impactful grind size can be. The details are literally granular. First, you can’t taste the shots we’re pulling. Second, once you’re grinding fine enough, the micron-scale differences that separate a great shot from a mediocre one all start to look the same to the naked eye.
Thankfully, we’ve got a tool for that. For this deep dive into all things coffee nerdery, we finally got to break out our new fancy DiFluid Omni particle size analyzer (thanks, Clive) and reveal what we’ve been working on for several weeks. It’s an incredible piece of equipment to work with, and we felt it was justified to splurge to give you a more data-driven and detailed analysis of how the minutiae of particle size have an enormous impact on your espresso outcomes.
Finally, a device that lets us bypass our fallible vision and see just how different grinders, grind settings, and even coffees affect particle size distribution—and, in turn, get a visual representation of the data that is easy to digest.
The Basics of Particle Size Analysis
This particle analyzer works fairly straightforwardly. You take a small sample of ground coffee, place it on a white tray, position the device over it, and press go. The device vibrates to evenly distribute the grounds, then uses a camera and lights to analyze and count each tiny particle. Within seconds, it delivers both a pie chart and a bar graph, giving us a precise look at the average grind size and how consistent the distribution is.
Why does this matter? Because in coffee, we’re always chasing even extraction. It’s easier to extract flavor consistently from evenly sized particles than from a mix of large and small ones. A narrower distribution means fewer under or over-extracted grounds, leading to a cleaner, more balanced shot. With that in mind, let’s dive into some practical real-world comparisons.
How Bad Are Blade Grinders?
First up: a battle between two wildly different grinders—a Krups blade grinder and the LUCCA Atom burr grinder.
If you’ve ever used a blade grinder, you probably already know where this is going. Blade grinders grind coffee in the loosest sense of the word, hacking beans into an unpredictable mix of fine dust and coarse chunks. This style of grinding is much better for spices. As expected, our analysis showed that while the grounds might look somewhat uniform, the blade grinder produced a chaotic spread of particle sizes, with a heavy concentration at both the ultra-fine and coarse ends. This means you end up with over-extracted bitterness and under-extracted sourness in the same cup.
So, let’s make it definitive: if you’re making espresso, please don’t use a blade grinder.
Same Grinder, Different Brew Brew Ratios
Next, we stuck with the LUCCA Atom 75 to see how it performs at two drastically different grind settings. For the first sample, we dialed in a concentrated 1:1.5 ratio shot. We dialed in a larger and faster 1:3 ratio shot for the second shot. Side by side, the difference in grind size is subtle to the naked eye. However, the particle-size analyzer tells a clearer story, illustrating how much those slight changes in grind size impact extraction.
This round highlights just how precise espresso grinding is. The difference between these two shots is just a few tens of microns, which is a fraction of the width of a human hair—tiny, but just enough to change how water interacts with the coffee.
Do Bigger Burrs = Better Espresso?
The short answer is yes.
Yet, how do we perceive this supposed improvement in the real world? To see this in action, we compared the Eureka Mignon Zero, with its 55mm burrs, to the LUCCA Atom, which has 75mm burrs. You may ask if this makes a difference in the home setting. If you're chasing better espresso, dear reader, it makes all the difference.
Compared to the blade grinder, the difference between these two is subtle. But the data shows a clear reduction in both the finest and coarsest particles with the larger burrs. This small change leads to more even extraction, and that’s why so many baristas chase those 65mm+ burrs for “café-quality” shots.
Flat vs. Conical Burrs
Lastly, let's wade through one of coffee’s longest-running debates: flat burrs versus conical burrs, and see if we can get any clarity from the data. Each produces a distinct particle size distribution, and this difference directly affects flavor. Flat burrs tend to create a monomodal distribution, with most particles clustering around a single size. Conical burrs, on the other hand, produce a bi-modal distribution with two distinct peaks.
To test this, we compared the LUCCA Atom (flat burr) and the Weber Key (conical burr). Looking at the data, the contrast is striking. The flat burr’s even distribution versus the conical burr’s dual peaks is precisely what coffee geeks have been describing for years. Both grinders make incredible espresso, but this data helps explain why conical burr shots often taste different from their flat burr counterparts.
What Does This All Mean?
Do you need a particle-size analyzer in your home setup? The short answer is absolutely not. Yet, we wouldn't pass judgment if you want to add it to your repertoire of tools.
A particle analyzer would best fit production and café settings, but for a home barista, they’re total overkill. What they do show, though, is just how precise and sensitive espresso grinders need to be. The fact that a few microns of difference can change your extraction proves just how intense espresso is as a brew method. It also highlights the insane level of engineering that goes into high-end grinders and why they’re so important.
If you’re just getting into espresso, we hope this gives you a better understanding of why particle size matters and why investing in a quality grinder is always worth it. This was just a first look at what a particle-size analyzer can tell us, and we’ve barely scratched the surface. Expect plenty more experiments in the future.