# Sieving Grinds



## fluffles (Sep 4, 2012)

Hi,

Just wondered whether anyone goes to the length of sieving their grinds before brewing? It seems logical that getting rid of the very fine fines would give a more even extraction, but I haven't heard much mention of it around here.


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## froggystyle (Oct 30, 2013)

There was a thread on this a while ago...

http://coffeeforums.co.uk/showthread.php?18380-Micron-Sieve&highlight=sieving


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## The Systemic Kid (Nov 23, 2012)

Micron sieves are a pain, frankly and expensive. A simpler and cheaper option is to use a stainless steel flour sieve - will take out the fines and produce a more balanced cup.


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## Beanosaurus (Jun 4, 2014)

Don't forget the boulders too - a lab coat and refractometer would also fit the look.


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## The Systemic Kid (Nov 23, 2012)

You referring to Boots??


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## MWJB (Feb 28, 2012)

Sieves of a given mesh size can be used to identify typical grind size distributions (has been done for decades), as well as to eliminate boulders & fines. Sometimes you might find cook's sieves with a specific mesh size, cheaper than sieves used in motorised sieve shakers.


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## xygorn (Feb 10, 2015)

I just started sieving this week with a metal flour sieve. I have been sifting out ~3g of fines from 19g of beans ground with my Hario Mini. If you want to try it, my first piece of advice is that you will have to adjust your brewing parameters substantially (I doubled my extraction time and increased temperature by 2-3 degrees to compensate).

In principle, I do not think that having a perfectly uniform grind will give you the perfect coffee, since there is no reason that the relative solubility of compounds would necessarily result in the best flavour profile. Ideally you would be able to specify exact ratios of fine, medium, and coarse grinds to optimize which how much of each flavour compound you want. For example, if you want a little bit more bitterness/astringency for balance and a little more acidity, you could increase the fines a little (for bitter compounds) and increase the coarse grinds (for acidity). This would give you finer control than decreasing temperature or extraction time, which changes the extraction from all of the grounds at once. This would be pretty hard to optimize though.

In practice, I know that I needed to reduce the fines in my brew, so sifting helped me to achieve that.

-Ziggy


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## Beanosaurus (Jun 4, 2014)

xygorn said:


> I just started sieving this week with a metal flour sieve. I have been sifting out ~3g of fines from 19g of beans ground with my Hario Mini. If you want to try it, my first piece of advice is that you will have to adjust your brewing parameters substantially (I doubled my extraction time and increased temperature by 2-3 degrees to compensate).
> 
> In principle, I do not think that having a perfectly uniform grind will give you the perfect coffee, since there is no reason that the relative solubility of compounds would necessarily result in the best flavour profile. Ideally you would be able to specify exact ratios of fine, medium, and coarse grinds to optimize which how much of each flavour compound you want. For example, if you want a little bit more bitterness/astringency for balance and a little more acidity, you could increase the fines a little (for bitter compounds) and increase the coarse grinds (for acidity). This would give you finer control than decreasing temperature or extraction time, which changes the extraction from all of the grounds at once. This would be pretty hard to optimize though.
> 
> ...


Strong 5th post right there.


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## MWJB (Feb 28, 2012)

xygorn said:


> In principle, I do not think that having a perfectly uniform grind will give you the perfect coffee, since there is no reason that the relative solubility of compounds would necessarily result in the best flavour profile. Ideally you would be able to specify exact ratios of fine, medium, and coarse grinds to optimize which how much of each flavour compound you want. For example, if you want a little bit more bitterness/astringency for balance and a little more acidity, you could increase the fines a little (for bitter compounds) and increase the coarse grinds (for acidity).
> 
> -Ziggy


Interesting thoughts but bitterness & astringency don't have a single root cause, you can get pithiness at under, or overextraction. Even so, if your grinds were abnormally uniform, surely you could steer the whole brew more accurately & evenly towards your taste? A lot of folk would attribute abnormal bitterness or acidic (acidity is more a question of bean/roast/terroir) tastes as results of a degree of malfunction...why not decrease the level of malfunction whilst pursuing your preference? Some are of the opinion that defects in the brewing process actually hinder revealing the bean's taste, rather than add nuances (underextraction & overextraction tend to have more of a generic effect on flavour, tasting more similar from bean to bean, than the distinctive bean flavour).

In his grinder presentation at the Nordic Barista Cup, Randy Pope of Bunn brewed some samples for the attendees to taste, the overwhelming preference for the sample brewed from selected sieves (excluding boulders & fines) even seemed to take him by surprise.


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## aaronb (Nov 16, 2012)

Im sure I read or watched something recently about espresso grinders where they said a distribution including fines and boulders actually produced better results in the cup then a more uniform grind, but cant remember what it was now


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## MWJB (Feb 28, 2012)

Espresso grind naturally consists of a degree of fines & boulders, as any grinder set fine will normally produce a secondary fines peak (bi-modal). Sieving espresso is supposed to get more tricky than for say drip, because the bulk of the grind distribution will be under 400-600um & sieves don't work so well for separating very fine grinds.

More boulders (than typical) will mean more underextracted larger particles and a lower limit on good tasting extraction. Perger wrote that he thought the larger boulders were more responsible for slowing flow...this is probably related to the gloopier, thicker shots from a wider distribution, as the oils extract quickly & possibly more oily content is derived from the boulders, compared to later extracts?


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## fluffles (Sep 4, 2012)

MWJB said:


> Interesting thoughts but bitterness & astringency don't have a single root cause, you can get pithiness at under, or overextraction. Even so, if your grinds were abnormally uniform, surely you could steer the whole brew more accurately & evenly towards your taste? A lot of folk would attribute abnormal bitterness or acidic (acidity is more a question of bean/roast/terroir) tastes as results of a degree of malfunction...why not decrease the level of malfunction whilst pursuing your preference? Some are of the opinion that defects in the brewing process actually hinder revealing the bean's taste, rather than add nuances (underextraction & overextraction tend to have more of a generic effect on flavour, tasting more similar from bean to bean, than the distinctive bean flavour).
> 
> In his grinder presentation at the Nordic Barista Cup, Randy Pope of Bunn brewed some samples for the attendees to taste, the overwhelming preference for the sample brewed from selected sieves (excluding boulders & fines) even seemed to take him by surprise.


I don't want bitterness in my brewed coffee - I want sweetness balanced with a nice acidity. Having read some of Matt Perger's articles his argument seems to be if you have a uniform grind then you should try and extract way more than you usually would as you don't have the fines skewing the extraction by going way over. This makes sense I think.

I've had a go with my kitchen sieve this morning and the result was promising. Went much finer on the grind and hotter on the water and yet it was not over-extracted (to my palate) and it still completed in 2:30 (Matt Perger V60 method on Kalita Wave), so I think the theory may work out in practice. I'm going to get hold of a 250 micron sieve and give it a proper go (my kitchen sieve lets too much through).


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## MWJB (Feb 28, 2012)

fluffles said:


> I don't want bitterness in my brewed coffee - I want sweetness balanced with a nice acidity. Having read some of Matt Perger's articles his argument seems to be if you have a uniform grind then you should try and extract way more than you usually would as you don't have the fines skewing the extraction by going way over. This makes sense I think.


Yes, it's a logical progression, as you eliminate less than ideal particles, your target yield for good extraction can rise (indeed, it may have to) as there's less of a compromise regarding average extraction, with overextracted fines & underextracted boulders.


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## bpchia (Dec 23, 2014)

I asked Matt Perger a question about sifting for filter by email and he responded "re sifting, 75% of your extraction comes from particles smaller than 110um. A 450um sieve would literally pour 85% of your extraction potential in the bin."

I wasn't able to get him to clarify that, but perhaps he was referring to espresso? So what size sieve is needed to remove some of the fines?


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## The Systemic Kid (Nov 23, 2012)

Don't think MP is referring to espresso. You're not going to find 450um sieves cheap. You can find Ebay aquarium sieves in a range of um sizes but you would soon get fed up with all the faff as you would be shaking for ages to get the fines out. Try a cheap kitchen flour sieve for starters - doesn't cost much and will certainly cut out a percentage of fines and as a result reduce extraction yield.


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## MWJB (Feb 28, 2012)

250um is often quoted for manual drip. SCAA drip grind (fairly coarse) regards anything under ~600um as "fines" (18% of grinds weight), Euro drip anything under ~400um (20% of grinds weight).

Randy Pope's experiment, menioned above, used grinds between 850um & 1180um (very narrow range). Depends on how much you can slow the flow rate, by breaking up the pours & keep a decent level of extraction...& how much coffee you are prepared to bin (may have been ~50% in Pope's case?)?


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## bpchia (Dec 23, 2014)

Is the cheap kitchen flour sieve the one where you pull a lever on the handle and it agitates the flour to sift it all through?


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## bpchia (Dec 23, 2014)

I'm currently using a V60-01 but getting a Kalita Wave 155...I've got a Lido 2 hand grinder. Do you think the cheap kitchen flour sieve is probably a good thing to do if I can be bothered?


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## MWJB (Feb 28, 2012)

http://www.lockhartcatering.co.uk/kitchen-equipment/triturators-chinois-sieves-strainers/e3645/cooks-sieve-0-5mm-mesh-polypropylene-30cm/

They are out of stock of some useful mesh sizes, 30cm are huge.


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## bpchia (Dec 23, 2014)

But why was MP saying that 75% of extraction comes from


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## The Systemic Kid (Nov 23, 2012)

bpchia said:


> Is the cheap kitchen flour sieve the one where you pull a lever on the handle and it agitates the flour to sift it all through?


Something like this

http://www.amazon.co.uk/s/?ie=UTF8&keywords=mesh+sieve&tag=cfukweb-21&index=kitchen&hvadid=31517879960&hvpos=1t1&hvexid=&hvnetw=g&hvrand=2640071823137717984&hvpone=&hvptwo=&hvqmt=b&hvdev=c&ref=pd_sl_55jckm7y3s_b

Used to sieve the grinds from a Mahlkonig Vario fitted with steel burrs using one of the above to bring down the extraction yield for brewed coffee (fines extract more due to their overall large surface area - weight for weight for particle size larger than this). Also use a refractometer to check results aiming for a yield of 19-19.5% which fitted my taste preferences. Without a refractometer, you are relying on taste alone - not a problem but perhaps harder to get consistency without a refractometer.


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## The Systemic Kid (Nov 23, 2012)

bpchia said:


> But why was MP saying that 75% of extraction comes from
> 
> if you had a dose comprising particle size of only 100um, dose of 150um, dose of 200um etc - you would find the smallest um size would extract the most because weight for weight, the smaller the particle size will have the greatest surface area so extracts more.


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## Dylan (Dec 5, 2011)

Are there any reflectometers for coffee that aren't in the "how much?







" price range?


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## jeebsy (May 5, 2013)

Dylan said:


> Are there any reflectometers for coffee that aren't in the "how much?
> 
> 
> 
> ...


http://coffeeforums.co.uk/showthread.php?20285-Brix-Refractometer


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## Lefteye (Dec 30, 2014)

Instead of binning the fines why not try a quick aeropress. Surely if extraction of larger particles takes longer the fines could be extracted v quickly. Could you not get the aeropress ready dump the grinds stir and extract in less than 30 secs and see what happens with that. I might try this with both ends of the spectrum.


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## Lefteye (Dec 30, 2014)

I could be talking rubbish though and am happy to be told that (nicely)!


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## The Systemic Kid (Nov 23, 2012)

You'd need to grind kilo(s) to get 10-15grms of fines.


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## Dylan (Dec 5, 2011)

jeebsy said:


> http://coffeeforums.co.uk/showthread.php?20285-Brix-Refractometer


I read that thread back when it cam up, my reading was "Yes you can get other cheaper tools, but none of them are really worth getting". The primary reason being no software to actually produce meaningful results from.


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## Lefteye (Dec 30, 2014)

Doh!! I forgot how light they were!


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## MWJB (Feb 28, 2012)

Lefteye said:


> Instead of binning the fines why not try a quick aeropress. Surely if extraction of larger particles takes longer the fines could be extracted v quickly. Could you not get the aeropress ready dump the grinds stir and extract in less than 30 secs and see what happens with that. I might try this with both ends of the spectrum.


The sieved grinds will underextract in this scenario, most likely so will the fines...the stir will mix the grinds/fines & water & in that 30seconds (seems a tall order to fill, stir & plunge, completing in 30s) you will have a weak but significantly extracted coffee solution, this won't pick up as much dissolved solids as you plunge like it would if you were washing out the grinds with fresh brew water (drip), or passing brew water under pressure through the fines bed.


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## Dylan (Dec 5, 2011)

Dylan said:


> I read that thread back when it cam up, my reading was "Yes you can get other cheaper tools, but none of them are really worth getting". The primary reason being no software to actually produce meaningful results from.


More reading shows that the cheaper Brix meters do have their place, and convert fairly accurately to TDS.

http://coffeegeek.com/forums/coffee/machines/203992?LastView=1424351309&Page=1


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## jeebsy (May 5, 2013)

Dylan said:


> More reading shows that the cheaper Brix meters do have their place, and convert fairly accurately to TDS.
> 
> http://coffeegeek.com/forums/coffee/machines/203992?LastView=1424351309&Page=1


That's almost ten years old. MWJB knows his shit and said in the other thread the Brix and meters aren't much use.


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## MWJB (Feb 28, 2012)

Dylan said:


> More reading shows that the cheaper Brix meters do have their place, and convert fairly accurately to TDS.
> 
> http://coffeegeek.com/forums/coffee/machines/203992?LastView=1424351309&Page=1


That thread predates the VST coffee refractometer. They didn't know then what we know now...primarily that Brix does not convert accurately to coffee TDS. Even Atago state on their brix refractometer info "brix/concentration may not be indicative of yield". You can multiply brix by whatever factor you like, you just get brix x "whatever", not TDS.

A lot of folk find their preference for a brew method might be +/- 1.0 to 1.5% extraction yield, there isn't a brix refractometer that can even ensure you are within +/- 2% which isn't really enough to give you meaningful, repeatable info, nor even ensure that a mid box reading means a brew that's in the box at all.


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## Dylan (Dec 5, 2011)

jeebsy said:


> That's almost ten years old. MWJB knows his shit and said in the other thread the Brix and meters aren't much use.


Edit: nevermind, already an explanation from MWJB


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## MWJB (Feb 28, 2012)

Dylan said:


> I saw that, and what MWJB said. Is there a breakdown of where the Brix reading falls apart or to what extent, if any, it may be useful..?


The primary reason for taking TDS isn't so much to know what your TDS is (preferences aren't constant across brew methods), it's the mechanism that helps you determine extraction yield which is much more indicative of preference over a very wide range of TDS.

Even if you had an accurate TDS, it's no good without a mechanism to turn it into an accurate extraction yield. You can compare brix readings from brew to brew, but it seems a very expensive way of getting a result that you can't share. The VST seems expensive, but in terms of value for money & equally accurate lab gear (even more expensive refractometers costing thousands, dehydration ovens & accurate scales) it's relatively cheap.


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## bpchia (Dec 23, 2014)

The Systemic Kid said:


> Something like this
> 
> http://www.amazon.co.uk/s/?ie=UTF8&keywords=mesh+sieve&tag=cfukweb-21&index=kitchen&hvadid=31517879960&hvpos=1t1&hvexid=&hvnetw=g&hvrand=2640071823137717984&hvpone=&hvptwo=&hvqmt=b&hvdev=c&ref=pd_sl_55jckm7y3s_b
> 
> Used to sieve the grinds from a Mahlkonig Vario fitted with steel burrs using one of the above to bring down the extraction yield for brewed coffee (fines extract more due to their overall large surface area - weight for weight for particle size larger than this). Also use a refractometer to check results aiming for a yield of 19-19.5% which fitted my taste preferences. Without a refractometer, you are relying on taste alone - not a problem but perhaps harder to get consistency without a refractometer.


Which one? There's over 400 results! Thanks


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## The Systemic Kid (Nov 23, 2012)

All much the same - cheap and cheerful plastic at around £3.75 or metal at around £9.00.


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## jjprestidge (Oct 11, 2012)

Max and Chris Hendon from University of Bath are investigating particle size uniformity and its effects on extraction at the moment. Unfortunately, it looks to be more complicated than we thought originally, and fines are not necessarily as negative as they may have seemed.

JP


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## The Systemic Kid (Nov 23, 2012)

Look forward to hearing more about this.


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## xygorn (Feb 10, 2015)

Anecdotally, I just started sieving recently. Without the fines, I had trouble getting the intensity of flavour I wanted, despite increasing extraction time (although I didn't push to very long extraction times). Based on the advice of MWJB, I added the fines back in later in the extraction, and made two of the best coffees I've made so far:

Inverted Aeropress, 95C water, 1:10 brew ratio (I like it strong), 2 minute extraction without fines, then 45 seconds more with fines added back in. I tend to like my coffee with high acidity, so you might want to go hotter or longer than I do.


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## The Systemic Kid (Nov 23, 2012)

xygorn said:


> Anecdotally, I just started sieving recently.


Would be interesting to hear what you use.


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## jeebsy (May 5, 2013)

The Systemic Kid said:


> Would be interesting to hear what you use.


A sieve (boom boom)


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## xygorn (Feb 10, 2015)

The Systemic Kid said:


> Would be interesting to hear what you use.


It was a metal sieve from Morrisons, and cost about 3 quid.


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