<p>Coffee-guru-slash-astrophysicist Jonathan Gagné wrote a Python script that analyzes a photograph of ground coffee, and generates histograms by particle size. It has some flaws. It will miss the finest fines completely, for example, but it's interesting enthusiast level stuff, and it's free software.</p>
<p><a href="https://i.sstatic.net/Tll3t.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Tll3t.png" alt="histogram of available mass by surface area" /></a></p>
<p><a href="https://coffeeadastra.com/2019/04/07/an-app-to-measure-your-coffee-grind-size-distribution-2/" rel="nofollow noreferrer">https://coffeeadastra.com/2019/04/07/an-app-to-measure-your-coffee-grind-size-distribution-2/</a></p>

CC BY-SA 4.0
2022-08-18T22:27:38.743Z
Very cool!  Thanks.
fixer1234
CC BY-SA 4.0
2022-08-18T20:33:31.077Z
2022-08-18T20:33:31.077Z
Salt
<p>If you own an AeroPress, there's an easy way to do it.  I discovered this in the process of making coffee stain from spent grounds.</p>
<p>The grounds settle to the bottom of the brew by size; the bigger the particle, the faster it settles to the bottom.  However, in the initial brewing, it isn't a clean separation because gas released by the grounds buoys some of the grounds.  That doesn't happen if you repeat the process with spent grounds (you wouldn't want to drink the result, but you can still extract a lot of color to make stain).  Here's a process to see the particle size distribution:</p>
<ul>
<li><p>After brewing the coffee, capture all of the spent grounds.  The cake can be knocked off into a container, but some will stick to the filter and plunger.  Rinse those with a little water into the same container.</p>
</li>
<li><p>Add some water to the container, enough so the grounds can be well stirred into the water, so it isn't like a paste.  When I make coffee stain, I microwave this mixture to cook more of the color out of the grounds, which may leave them more water-logged.  You can try this with ot without microwaving to see if that makes a difference in the particle separation.</p>
</li>
<li><p>Prepare the AeroPress for upright brewing (you can rinse and reuse the original filter for this purpose or use a fresh one).</p>
</li>
<li><p>Stir and pour the water/grounds mix into the AeroPress, scraping the container to get all of the grounds.</p>
</li>
<li><p>If necessary, add some more water to the AeroPress so there's plenty for disbursing the grounds.  Stir the mixture well and aggressively to get all of the grounds suspended in the water.</p>
</li>
<li><p>Insert the plunger at an angle to get it into the body without compressing the air.  That will seal the end and keep the water from draining out while the grounds settle.</p>
</li>
<li><p>Let the AeroPress sit for at least several minutes so the grounds settle to the bottom (5 minutes should be plenty).</p>
</li>
<li><p>Do a slow press all the way down, even compressing the cake a little, which will help it stay together.</p>
</li>
<li><p>Remove the strainer cap, and carefully remove the filter.</p>
</li>
<li><p>The coarsest particles will be on the filter and at that end of the cake.</p>
</li>
<li><p>Push the plunger all the way in to expose the cake, and knock it off onto something like a plate.</p>
</li>
<li><p>The fines are likely to act like glue and keep a thin layer of grounds stuck to the plunger.  Compare the exposed (non-fines) grounds stuck on the plunger or at that end of the cake to the grounds at the filter-end of the cake.  The size difference will show you the range of sizes the grinder is producing.</p>
</li>
<li><p>Carefully scrape the plunger onto the plate to push everything off as one intact piece.  What comes off will be a little like clay.</p>
</li>
<li><p>There is normally a gap in size between what the grinder is grinding and the fines (the fines are mostly dust that breaks off the beans when the beans are distorted during grinding; the grinder doesn't grind fines).  There will always be some amount of fines.  If the grinder is doing mostly cutting rather than crushing, the layer of fines will be a very small portion of the thickness of the cake.</p>
</li>
<li><p>The main usefulness of this technique is to see the size range that the grinder is producing.  You can theoretically treat the cake like a soil or ice core.  After you've compared the ends for particle size, you can shave off layers of the cake with a knife to get an idea of the amount of grounds at different sizes.</p>
<p>However, that's of limited usefulness.  Particles anywhere close to a medium grind settle out pretty fast.  Fine or very fine particles take a little longer.  In the race to the bottom, you get a distribution of particles that changes over time.  So there will be a thin layer at the filter end that is predominantly the largest particles, and a thin layer at the plunger end that will be predominantly the smallest particles.  In between will be a mix of sizes, the average of which will get smaller as you move through the cake.  Trying to judge particle size in the intermediate layers of the cake isn't a whole lot easier than judging it by spreading out the fresh grounds.</p>
</li>
</ul>
<p>With my own grinder, I set the size to a little finer than the size of standard pre-ground coffee for drip coffee makers.  The coarsest grounds my grinder produces are roughly like pre-ground coffee, and the finest are about what I set the grinder for.  Looking at the grinds as they come out of the grinder, it's hard to distinguish size differences in the pile, and it looks like it's all what I set the grinder for.</p>

CC BY-SA 4.0
2022-08-17T19:08:50.670Z
2022-08-18T17:58:38.470Z
2022-08-18T17:58:38.470Z
fixer1234
<p>The holy grail of coffee grinders is uniform particle size.  You can spread some grounds on a piece of paper and eyeball what's there.  There is also special equipment, like sieves, that will separate the particles into size ranges, and visual guides you can compare the grounds against.  But is there a simple way, without fancy equipment, to &quot;sort&quot; the grounds by size so you can see the size range and relative amounts?</p>

<grind-size>
Is there a simple way to see the distribution of particle sizes that my grinder produces?
fixer1234
# Is there a simple way to see the distribution of particle sizes that my grinder produces?

(Asked by: username_0 on 2022-08-17)

The holy grail of coffee grinders is uniform particle size. You can spread some grounds on a piece of paper and eyeball what's there. There is also special equipment, like sieves, that will separate the particles into size ranges, and visual guides you can compare the grounds against. But is there a simple way, without fancy equipment, to "sort" the grounds by size so you can see the size range and relative amounts?

**Tags:** grind-size


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## 2 answers

### Answer by username_1 on 2022-08-18. Score: 1

Coffee-guru-slash-astrophysicist Jonathan Gagné wrote a Python script that analyzes a photograph of ground coffee, and generates histograms by particle size. It has some flaws. It will miss the finest fines completely, for example, but it's interesting enthusiast level stuff, and it's free software.

[![histogram of available mass by surface area](https://i.sstatic.net/Tll3t.png)](https://i.sstatic.net/Tll3t.png)

<https://coffeeadastra.com/2019/04/07/an-app-to-measure-your-coffee-grind-size-distribution-2/>

> **Comments:**
> **username_0**: Very cool!  Thanks.  

---

### Answer by username_0 on 2022-08-17. Score: 0

If you own an AeroPress, there's an easy way to do it. I discovered this in the process of making coffee stain from spent grounds.

The grounds settle to the bottom of the brew by size; the bigger the particle, the faster it settles to the bottom. However, in the initial brewing, it isn't a clean separation because gas released by the grounds buoys some of the grounds. That doesn't happen if you repeat the process with spent grounds (you wouldn't want to drink the result, but you can still extract a lot of color to make stain). Here's a process to see the particle size distribution:

* After brewing the coffee, capture all of the spent grounds. The cake can be knocked off into a container, but some will stick to the filter and plunger. Rinse those with a little water into the same container.
* Add some water to the container, enough so the grounds can be well stirred into the water, so it isn't like a paste. When I make coffee stain, I microwave this mixture to cook more of the color out of the grounds, which may leave them more water-logged. You can try this with ot without microwaving to see if that makes a difference in the particle separation.
* Prepare the AeroPress for upright brewing (you can rinse and reuse the original filter for this purpose or use a fresh one).
* Stir and pour the water/grounds mix into the AeroPress, scraping the container to get all of the grounds.
* If necessary, add some more water to the AeroPress so there's plenty for disbursing the grounds. Stir the mixture well and aggressively to get all of the grounds suspended in the water.
* Insert the plunger at an angle to get it into the body without compressing the air. That will seal the end and keep the water from draining out while the grounds settle.
* Let the AeroPress sit for at least several minutes so the grounds settle to the bottom (5 minutes should be plenty).
* Do a slow press all the way down, even compressing the cake a little, which will help it stay together.
* Remove the strainer cap, and carefully remove the filter.
* The coarsest particles will be on the filter and at that end of the cake.
* Push the plunger all the way in to expose the cake, and knock it off onto something like a plate.
* The fines are likely to act like glue and keep a thin layer of grounds stuck to the plunger. Compare the exposed (non-fines) grounds stuck on the plunger or at that end of the cake to the grounds at the filter-end of the cake. The size difference will show you the range of sizes the grinder is producing.
* Carefully scrape the plunger onto the plate to push everything off as one intact piece. What comes off will be a little like clay.
* There is normally a gap in size between what the grinder is grinding and the fines (the fines are mostly dust that breaks off the beans when the beans are distorted during grinding; the grinder doesn't grind fines). There will always be some amount of fines. If the grinder is doing mostly cutting rather than crushing, the layer of fines will be a very small portion of the thickness of the cake.
* The main usefulness of this technique is to see the size range that the grinder is producing. You can theoretically treat the cake like a soil or ice core. After you've compared the ends for particle size, you can shave off layers of the cake with a knife to get an idea of the amount of grounds at different sizes.

  However, that's of limited usefulness. Particles anywhere close to a medium grind settle out pretty fast. Fine or very fine particles take a little longer. In the race to the bottom, you get a distribution of particles that changes over time. So there will be a thin layer at the filter end that is predominantly the largest particles, and a thin layer at the plunger end that will be predominantly the smallest particles. In between will be a mix of sizes, the average of which will get smaller as you move through the cake. Trying to judge particle size in the intermediate layers of the cake isn't a whole lot easier than judging it by spreading out the fresh grounds.

With my own grinder, I set the size to a little finer than the size of standard pre-ground coffee for drip coffee makers. The coarsest grounds my grinder produces are roughly like pre-ground coffee, and the finest are about what I set the grinder for. Looking at the grinds as they come out of the grinder, it's hard to distinguish size differences in the pile, and it looks like it's all what I set the grinder for.


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