Posted Wed Nov 14, 2012, 12:24pm Subject: Re: Grinder Assessment Using Sieves
And here's a plot of the average grind (mean from the fit data) vs. Lido setting.
I hope to duplicate this data on my own LIDO, then duplicate for my modified Hario MMS, and my UNmodified HMMS - and finally my Bodum Bistro.
(Click for larger image)
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Posted Mon Nov 19, 2012, 8:46am Subject: Re: Grinder Assessment Using Sieves
Another interesting thing, SCAA states the standard grind for cupping is where 70-75% of the grind passes through a #20 Mesh sieve.
This is basically the 841micron sieve - and if you look at the cumulative distribution data: Click Here (www.coffeegeek.com)
only the settings at L-1.00 and L-0.75 have a chance at meeting this criteria. Except that this is pretty fine grind by eye and by feel. It extracts quickly. It's maybe equivalent to a Ditting set at 3-5.
Unless for some reason the cupping standards are supposed to have some gage of grind uniformity that's unrealistic.
This whole grind question - I'm beginning to regret looking into it... I get the feeling I'm generating more questions for myself than I'm answering. LOL
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Posted Mon Nov 19, 2012, 9:19am Subject: Re: Grinder Assessment Using Sieves
That official cupping standard has confused me a little in the past in that it does look finer than I'd expect--and if I'm not mistaken finer than I've seen used at the few formal cuppings I've been to.
Yeah, grind evaluation shares with espresso the potential for "down the rabbit hole" intractability. ;) No grind is truly uniform AFAIK.
Posted Tue Nov 20, 2012, 3:08pm Subject: Re: Grinder Assessment Using Sieves
I finally got a chance to poke some grounds with sieves.
Ditting KR804 set at 1 is Turkish grind. I only tried the #40, #60 and a little bit with the #100. These should be US Sieve numbers, so they should be 400 or 425micron, 250 micron and 150 micron respectively.
I understand the issues that OrphanEspresso had with fine grind. Gravity is not really good enough to get particles to sieve properly when the grind is so small. They stick together and just clump and wont pass through unless coerced. After mucking with it for quite a while, I did manage to use up my samples (I don't own a Ditting, I get samples ground), but I think I stumbled on something that is promising.
I did spend some time with a Sonicare toothbrush to vibrate the screen - eventually, I got pretty much all of the grind to get through 400 micron. Somewhere around half gets through 250 micron, so I expect this is close to the average grind size at this setting.
As a sense check, I used water to act as a sieve medium just to see - hoping that the water would rinse the particles and keep them from packing. I also knew that it would be swelling the particles, but was just playing around with it. It worked reasonably well, but is not practical. In a short time, I washed everything in a small scoop of Ditting-1 grounds through the 400 micron screen. I ended up with a significant amount of sharp, sandy particles that would either stick in or not pass through the 250 micron. After drying the particles, they were around 30% of the original mass - not accurate enough for precise work, and impractical as hell.
I began playing with rice and salt - I think there's something here. I reasoned that if I had particles that were about twice or more the size of the particles I was sieving, they might act like the primary sort sieves work - large particles rub against each other, prevent the small bits from clumping before they pass through the sieve, etc. But the particles aren't wet, so they won't cause the particles I'm sieving to swell (or extract! LOL). I sieved salt to make sure they were all trapped by the 400 micron sieve, then used 2 grams on the 250micron sieve, and 2 grams of rice on the 400 micron sieve. When I added 5 grams of Ditting-1, I got a trace in the pan, 55% stuck on the 150 micron sleeve, and basically just the mass of the rice on the 400 micron sleeve (plus maybe 0.05g, call it a trace).
So, I think that either is promising. When I have some more time, I'll try this with espresso setting on the Bodum and 0 on the Lido.
BTW, table salt has a trace trapped by the 500 micron sieve, about 60% trapped on the 400micron, a third or so on the 250micron, a trace on the 150 micron and a trace in the pan. This implies that according to the sieves I have - IF they are close to being standard number sieves - table salt is on average about 400micron +/- 100 micron.
I also got a chance to check a Ditting-9 and my Bodum at French Press.
Bodum set to +6 (French Press icon) 1.19; 6.00g 1.00; 2.46g 0.841; 2.1g 0.707; 0.71g 0.5; 0.82g Tray; 1.18g
Mean = 1.15mm, Sigma = 0.42
Notice the large difference in the variation - the Bodum has more variation as a Ditting set on normal recommendation for French Press. The particles are noticeably larger on the Bodum and sort of irregular for the >1.00mm group. I had so much in the >1.00mm for the Bodum (since the average was more than 1.00mm, more than half was trapped above it) I had to sieve that batch a second time with the additional 1.19mm screen.
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
Posted Tue Nov 20, 2012, 7:46pm Subject: Re: Grinder Assessment Using Sieves
Thanks for the great information. I have never been able to find any grind distribution figures for the Bodum.
I've been aiming for the 1.2mm to 1.5mm diameter peak grind that Nick Cho recommends with 6-8 minutes for french press.
I have also noticed those rather strange shapes on many of the larger particles when examining the grounds with a 20x loupe. I'm assuming this would speed the extraction slightly because of the larger surface area compared to a sphere.
Posted Thu Nov 29, 2012, 9:28am Subject: Re: Grinder Assessment Using Sieves
Steve, for some reason I was thinking about this thread earlier. Have you considered holding the beans constant when you're doing sieve analysis? Fines production is at least partially bean-dependent in my experience.
Posted Fri Nov 30, 2012, 5:46am Subject: Re: Grinder Assessment Using Sieves
jbviau Said:
Steve, for some reason I was thinking about this thread earlier. Have you considered holding the beans constant when you're doing sieve analysis? Fines production is at least partially bean-dependent in my experience.
Yes, I have. So far I haven't found a significant difference between performance of Eight o Clock 100% Colombia (my "lab standard" LOL ), Caribou Coffee Starlight, Home roasted (FC+) Ethiopia Yirg and Colombia, Starbucks Willow and Starbucks Christmas Blonde Blend. I only have limited amounts at any given time, so sieving hundreds of grams isn't exactly practical. I'm still trying to establish repeatability of the measurement system, and for that I'm basically using EoC 100% Colombia - available at any given time at local grocery.
Note that all of these are in the FC to FC+ range. It may be that it isn't necessarily the bean so much as the roast level that determines the friability of the bean. Darker roasted beans probably crack better (or maybe worse - maybe the darker roast produces more dust?), but lighter roasted beans are more "pliable". It does make me wonder if grinding cold (like freezer) beans vs. grinding warm beans make a significant difference.
...great. Another question that demands an answer. LOL
------------------------------------------ ----------------------------------------- Le café doit être noir comme le diable, chaud comme l'enfer, pur comme un ange, et doux comme l'amour.
"There is no right answer with coffee. There is only the elixir in your cup at the moment you partake."
"...I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind;..." - Lord Kelvin RECIPES thread => http://www.coffeegeek.com/forums/coffee/machines/585708
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