An experiment with grind size

My experience with the ExtractMojo has so far resulted in one recurring realisation:  I often wasn’t grinding finely enough.  The purpose of this isn’t to rehash the whole underextracted thing.  More a simple experiment in terms of people’s preferences.

Accurately communicating grind size remains near impossible.  We can say coarse, very coarse or fine or whatever, but it is still a pretty bad communicator when you are stood in front of a grinder that you don’t know.

If people are up for it then I’d like to try an experiment.  Pick a method that you know well.  Record how you are currently setting your grinder for your desired grind size.  Each time you brew it, keep everything the same (brew temp, water volume and steep time if applicable) but go a touch finer.  Keep going until you hit the wall of bitterness.  You’ll know it when you taste it, when the cup falls to pieces in a bitter finish.  Come back a touch coarser, and try a side by side brew of this grind Vs your original grind.  Which is better? Why?

I hope a few people will try this – it would be really interesting.  I am interested because if someone asked me the ideal grind size for the aeropress, for example, then I’d say to keep the steep time the same and bring the grind as fine as you can before it starts tasting noticeably bitter.

(I am quite prepared for you to all come back and tell me I am an idiot)

20 Comments An experiment with grind size

  1. Jason Dominy

    Excellent post. Definitely makes me want to try this out tomorrow. I’ve known for years that there was work to do with grind size, just never really put the work into working with it. I think now’s as good a time as ever. Thanks as always for inspiring James.

  2. kurt

    I would love to see you do an experiment on grind size for espresso. Specifically, I’m referring to a chapter in Rao’s book in which he asserts that by surfing the grind and dose down to 14 grams you can produce a sweeter, more balanced espresso. I have experimented with this informally and found it to be one of the most exciting, yet under-appreciated observations out there. The reliance on temperature programmable machines has taken the grind as a way to control nearly all brew parameters (not just the look of the extraction) out of the baristas arsenal.

  3. James Hoffmann

    I am not sure I quite understand your final sentence, but you are onto a very interesting subject that is deserving of a (long and) separate post.

    Barely 1% of espresso machines sold annually are used to brew more than 14g at a time. Espresso machines are built to do what the majority of users want them to do – which is extract 14g of coffee nicely. The basket, the machine, the dispersion of water etc etc – all are focused on a relatively small cake of coffee.

    You find that when you brew with this amount it is a lot easier to correctly extract the coffee (in terms of taste and use of the espresso version of the Mojo). The window of opportunity gets much bigger, blends get a little more tolerant and balanced. You don’t get the crazy, intense, syrupy mouthfeel of an updosed shot but I think many baristas are missing out by not pulling (or trying) lower dosed shots.

  4. Lee Wardle

    I tend to adjust the dosage dependant on the blend. I very much like the syrupy mouth feel of the upped dosage but a lower dose can make a more refreshing and of course lighter espresso. Again, it’s whatever makes the best of the espresso for me.

    As for the original post, I tend to agree with that.


  5. Lee Wardle

    I use french press quite a lot at home for convenience and it never occours to me to fine tune the grind too much. I wonder how many other people are like that. I’m analism personified when it comes
    to espresso ground. I shall have a play later too!

  6. Scott Lucey

    This is a home experiment I remember rattling my brain often in the past – mostly because I’d also associate it with the sharpness/dullness of one’s burrs.
    I can say I know I often ground too fine. My reasoning with that was that as my burrs got more dull, they’re ability to be precise and consistent became more difficult with a larger particle size. I’m guessing I preferred a slightly finer setting b/c I could visually notice more consistency of particle size.

    Also – Humorously so… My girlfriend and I have our own grind settings. Her preference is one setting coarser than mine.

  7. Mike

    Hi James, I have to say that I play with grind size quite regularly, primarily for filter brewing. I have found that using brewing technology (pulse brew or preinfusion) I can get the extraction I want (21-23.5% depending on the coffee) while keeping the grind relatively coarse. Though It’s possible to get a coffee to graph the same by adjusting the grind or the contact time, I find the finer grind tends to give a slightly harsher finish to the cup, so prefer to keep a slightly larger particle size and make my changes to contact time.
    I guess you would probably consider me something of a philistine but I do think that the lack of harshness allows a more complex coffee to develop.
    I’m interested to hear that you prefer a finer grind, and look forward to hearing some other points of view.


  8. James Hoffmann

    I am all for getting rid of harshness. I suppose this recommendation works best in a steep/infusion style brew – rather than percolation.

    I think it is quite fun how excited everyone is about pouring kettles when you could argue that a modern filter brew does better water dispersion, has better flow rate control and more overall control than many manual methods. The use of pulse brewing and playing with preinfusion/bloom is definitely an area I’d like to learn more.

    It could be that perhaps we could do a similar experiment by grinding coarser, and setting it there and then changing the contact time to be longer and longer to play with the extraction…

  9. Mike

    Trust me, pulse brew, pre-infusion and bypass open a whole host of possibilities. All of them repeatable and scaleable. The only downside is the perceived lack of artisanal input, which tends to be done ahead of time.

    The biggest problem with this amount of control is that very few people have the time to experiment enough to get the best from it.

  10. Sam

    I work as a barista in Montreal, from an espresso brewing point of view (I’m australian i should add) I’ve been experimenting with the dosage, grind and brew times. I’m finding when i dose 18 grams and run a ristretto I’m getting extreme crema and syrupy-ness… but I’m finding it almost “grainy” (for want of a better word) I find this detrimental… I’m not sure if I’m under drawing the grounds or not– I’m worried I am, but i can’t find anything in the taste to suggest I am (beside the mouth feel)…. this sounds stupid.

    However, I’m only bringing this up because the 14 gram dosage comments. Dosing 14 grams, finer grind, same run time, I’m getting the same crema, same sweetiness and desirable taste, but without this “grainy” mouthfeel. Its a direction I’ve convince my boss to roll with.

    anyone who can push me in the right direction much appreciated.

    * as a foot note i have a crap set up, not a great espresso machine, and beans are from Italy (Karalis… which is actually one of the better tasting beans I’ve tasted out of Italy) and I dont have the extract mojo gear… although I am familiar with it.

  11. Billy.411

    Haven’t been a barista for a couple of years now… but your ‘experiment was something we were trained to do several times throughout out the work day. As temperatures rose, machines heated up, humidity changed – we were encouraged to change the grind and run this test you have outlined.

    I kinda just got into the habit with my own coffees, to always grind a touch finer and then cut the the pours off a little shorter than ‘normal’ and top up with fresh hot water. I find this suits my coffee palate the best, as that last few mls of coffee is generally what puts it over the ‘acidity/bitter’ edge for me.

  12. AndyS

    > …pulse brew, pre-infusion and bypass open a whole host
    > of possibilities. All of them repeatable and scaleable.
    > The only downside is the perceived lack of artisanal input…

    Well said.

  13. Lee Wardle

    Are you talking about espresso Billy? That’s pretty normal but it would have never occoured to me to do the same with other infusion based brewing.

    I can’t get my my hands on some fresh beans until tomorrow at work so hopefully I’ll be able find time to have a play.


  14. Billy.411


    Yeah, sorry… guess I outed from that last comment a little early!

    What I meant is that the process that we use in Espresso machines can often be translated to other coffee brewing methods.
    Down the grind a touch, restrict the amount of water a little and top up with fresh hot water.

    Of course this isn’t always going to be able to be implemented in the working industry, but certainly to those of us at home with too much time on our hands – it’s nice to experiment.

  15. James Weeks

    I agree, I would love to hear your opinion on lower dosed espresso.
    i use the S.C dosing tools, and lately ive been using the #25 blade… dosing into a triple basket with a finer grind.
    i’ve never enjoyed espresso so much in my life! It has a much sweeter, rounder flavor.
    I do agree though, some of the mouth feel is sacrificed, but I know which I’d prefer!

  16. Yakster

    I started down the path of fining up the grind with my Clever Coffee Dripper and making some Brix measurements right before I found your post, so I’m going to continue to reduce the grind.

    Already I’m surprised at the improvement in flavor with what I’d guess would be too fine a grind. I haven’t hit the bitter mark yet.

    Great blog post, Jim

  17. Tom J.

    Hi James,

    funny to say this but I’ve discovered the same thing when playing with the Mojo, I was definitely grinding too coarse for my Chemex. Switching from 3 to a 1.5 on my Guatemala upped the TDS, but I have to say that the taste suffered a bit, there was noticable bitterness, something which was completly missing from the coarse grind extractions (then again those were weak in taste and underextracted). So a few days ago I’ve tried upping the dose a bit, but leaving the grind a notch coarser and the effects were really nice, more ‘juice’ less bitterness.

    Just as a side note in my opinion the amount of coffee used for a brew (not the coffee/water ratio, just the amount of coffee you are brewing at one time) affects the taste as it slows down the water flow through the ‘puck’. So a certain setting used with 30g might not work so well with 60g or more. Again experiment and see for yourself.


  18. Dr PeterR

    Isnt the problem that all these things are so interdependent

    if you make the grind finer
    you need to decrease your portafilter fill
    you make need to alter the time allowed for extraction

    i find that there is a really narrow window of grind/volume of coffee I can get in my portafilter and my grinder (Rancilio rocky) is doserless – so it’s always an eyeball job to see if you’ve got enough or too much.

  19. Luigi

    Sorry to jump off the topic of the thread :) but in regards to the whole 14 versus 18 grams or more topic, I am compelled by the whole nature of discovery that occurs outside of Italy. On the one hand, exploration and experimentation is vital to our industry, and when it boils down to it, has increased the overall quality of coffee served out there, tremendously, in recent years. But to what extent are the Italians just sitting over there saying …” I told you so” this whole time? There is an interesting anecdote in Rao’s book about this.

    I’m first generation Italian – American, so I feel comfortable speaking from both sides of the equation here.

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