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Thread: Grinds

  1. #1
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    Grinds

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi,

    Id need some theory about grinding coffee beans, being unsure how fine the grind should be. I heard that the ideal extraction time for an espresso (ristretto) should be around 25 seconds. If longer, then tamp it less or grind the beans coarser, if shorter, tamp it more strongly or make the grind finer.
    Heres what I notice: sometimes, even though Im using the same grind, the result will vary, giving me overflow or overextraction. At other times, the coffee flows out beautifully but then tastes surprisingly bitter. When that happens I almost always observe grounds at the bottom of my cup.
    Id like to make the most of my coffee, so what do I do wrong? Should I grind it differently on rainy days? Id appreciate your inputs.

    PS: I have a machine based on a E61 group, a Mazzer Mini grinder, top quality coffee in top condition (fresh and all)

  2. #2
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    Re: Grinds

    When you say "coffee flows nice", if you mean it starts out very slowly and a solid brown colour, slowly increasing to a solid flow and slowly going lighter in colour, over the approx 20-30 seconds, but not going very pale yellow, which indicates blonding and overextraction, then if it tastes bitter it may be the brew temp was too high.* This is not uncommon in HX machines that have been sitting idle for a while, and can easily be overcome by flushing some water through the the group to bring it back to normal brewing range, before actually pouring the shot/s....the water can be used to preheat the cup/s you are going to use.
    Yes you will need to do some adjusting of grind size, depending on ambient temperature and humidity,... Lower humidity and/or higher ambient temperatures generally require finer grind, but high humidity(raining) and/or lower ambient temperatures generally require courser grind.
    If you have some fine grinds in your cup it is possible that the burrs in your grinder are giving uneven grinding, and there are some small fines amongst the grinds.

  3. #3
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    Re: Grinds

    I mean it really looks like liquid gold, amber brown, dense, etc. I always do a group flush and the machine hasnt been idle for at least a year and a half.
    Thank you for your reply

  4. #4
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    Re: Grinds

    Quote Originally Posted by 5651555D5156515D595C49300 link=1301871652/0#0 date=1301871652
    If longer, then tamp it more strongly or grind the beans coarser, if shorter, tamp it less or make the grind finer.
    I think youve got it the wrong way around regarding tamping. If its longer than 30seconds, you should be tamping with less pressure, and if its less than 20, you should be tamping with more pressure.
    That said however, try to vary the grind size as opposed to the tamp pressure, as it eliminates one variable.

    Also, keep your dose constant each time to achieve consistent results,

    Best of luck,

  5. #5
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    Re: Grinds

    I wont rehash what has just been said about temperature, but the important thing for me is only change one thing at a time, accepting that grind will need to be changed regularly. Tamp the same, dose the same, adjust grind to affect flow.

    You havent mentioned what machine or grinder or tamper you are using, and this could be a big factor in the advice given here.

  6. #6
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    Re: Grinds

    Quote Originally Posted by 445B59435A4F58594E360 link=1301871652/4#4 date=1301910652
    You havent mentioned what machine or grinder or tamper you are using, and this could be a big factor in the advice given here.
    The type of coffee, and how fresh it is could also play a major part.
    Also, if its tasting surprisingly bitter, you may be letting the shot run for too long. You should try to cut the shot as soon as blonding creeps in regardless of the volume extracted.

  7. #7
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    Re: Grinds

    Quote Originally Posted by 28233B312D2C2E272D35420 link=1301871652/3#3 date=1301910403
    I think youve got it the wrong way around regarding tamping. If its longer than 30seconds, you should be tamping with less pressure, and if its less than 20, you should be tamping with more pressure.
    That said however, try to vary the grind size as opposed to the tamp pressure, as it eliminates one variable.
    ,
    Thats what I meant, it was a mistake.

    As I added in the original post, I have a Mazzer Mini grinder, and the beans are a very fine product from Haiti.

  8. #8
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    Re: Grinds

    Quote Originally Posted by 0B0018120E0F0D040E16610 link=1301871652/3#3 date=1301910403
    Quote Originally Posted by 5651555D5156515D595C49300 link=1301871652/0#0 date=1301871652
    If longer (than 25 secs), then tamp it more strongly or grind the beans coarser, if shorter (than 25 secs), tamp it less or make the grind finer.
    I think youve got it the wrong way around regarding tamping. If its longer than 30seconds, you should be tamping with less pressure, and if its less than 20, you should be tamping with more pressure.
    I think they got it right (I did read it twice myself when they first posted).

    Read it again with my addition which refers back to the previous sentence.

    Make sense now?

  9. #9
    Senior Member trentski's Avatar
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    Re: Grinds

    Your beans come from Haiti? How many days since the day they were roasted are you using them?

    Is it a very dark roast?

  10. #10
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    Re: Grinds

    Just on Tamping....

    Tamping force per se doesnt really have a lot to do with the nature of the pour providing you use enough force in the first place to form a cohesive coffee puck in the basket.

    Since the most oft quoted Tamping Force Standard is 30lb or as often expressed here in Oz (in rough terms), 13.5Kg, the latter will be the value used. When this force is applied via the Tamper to a correct dose of coffee in a standard 58mm Filter Basket, it equates to a surface pressure on top of the coffee puck of 0.51Kg/cm2.

    Compare this then, with the force being applied to the puck when 9 Bar of water pressure is applied to the surface of the coffee puck. 9 Bar is equivalent to 9.18Kg/cm2 or a Total Applied Force of 242.54Kg. So when you look at it like this, the initial applied Tamping Force is barely over 5% of what is applied when you hit the Brew Switch (or equivalent).

    Probably the most you would notice between a soft tamp and a handstand tamp would be the time it takes before you observe coffee starting to drip from the spout but after that, its all about the force being applied by the pump.

    Just something worth noting... ;)

    Mal.

  11. #11
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    Re: Grinds

    Interesting theory mal, but empirical testing suggests it is not always the case.

    I do find that tamping harder than normal makes very little difference to the pour rate, but that is because I tend to tamp quite hard in the first place and have a slightly coarser grind than some.
    When I went on a barista training course, the first shot I tried to pull choked completely (30 sec and only a couple of drips) - the grinders had been preset and run to fil the doser.
    Using a light tamp allowed me to get a good pour rate.

    Im sure your calculations are accurate, but I suspect the fact the tamper is a solid object and water is able to percolate through the grounds has some bearing.


  12. #12
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    Re: Grinds

    Not a theory mate, totally factual..... 8-)

    Mal.

  13. #13
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    Re: Grinds

    Quote Originally Posted by 45686C606D010 link=1301871652/9#9 date=1302010223
    Tamping force per se doesnt really have a lot to do with the nature of the pour providing you use enough force in the first place to form a cohesive coffee puck in the basket.
    Not a theory mate, totally factual..... 8-)

    You didnt take into account the first paragraph, especially the highlighted section.

    Mal.

  14. #14
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    Re: Grinds

    A light tamp that forms what I consider a cohesive puck - 30ml in 30sec with the preground coffee provided to me (tamp somewhere around 10-12kg from memory)
    A heavy tamp that also forms a cohesive puck approx 1 ml in 30sec.
    Only saying what I experienced in a real world situation.

    I do agree that there comes a point where additional tamping force has marginal effect, which is something below my normal tamping force. Just for grins, I measured it on the bathroom scales, I normally tamp around 15-16kg. This would suggest the point at which increased tamp force has relatively little impact is between the 12kg and 15kg force.

    Im still convinced that the application of force by a fluid on a mass of particles is fundamentally different to that of a flat stainless tamper, but fluid dynamics was never one of my strengths so explaining the details is beyond me.

  15. #15
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    Re: Grinds

    Yep, no doubt tamp pressure has a very real and obvious impact on the pour. Its simple enough to demonstrate, use the same amount of coffee, with the same grind settings and time the pours. The more pressure with the tamp the longer the pour.

    Ultimately its not what pressure you tamp at that is so important as the consistency of your tamp. I used to tamp at around 30lbs and overdose, now I dose at around 14g and tamp at about 15lbs as I prefer the flavours I am getting.

  16. #16
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    Re: Grinds

    Quote Originally Posted by 41474A534B475F260 link=1301871652/14#14 date=1302088206
    now I dose at around 14g and tamp at about 15lbs as I prefer the flavours I am getting.
    Do you all pull only double shots? Because I do singles, is that ill-advised?


    Trentski,
    they are Haiti Komet from Giamaica Caffè, Verona, Italy, normal dark brown. I buy 10 kg at a time so it goes from 2 or 3 weeks since they were roasted to 2 or 3 months. But they are kept vacuum packed and in a refrigerator all the time.

  17. #17
    Mal Dimal's Avatar
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    Re: Grinds

    Quote Originally Posted by 4048464E4C56564A464E250 link=1301871652/13#13 date=1302087825
    Im still convinced that the application of force by a fluid on a mass of particles is fundamentally different to that of a flat stainless tamper, but fluid dynamics was never one of my strengths so explaining the details is beyond me.
    Yes it is different, more like applying pressure to a fine screen or membrane.... The thing is, Im referring to a tamp applied with a force that is considered to be the standard, namely 13.5Kg in round numbers. Forces applied within +/- 15% of this have little effect on the subsequent pour rate and especially where greater forces are concerned, you fast disappear over the horizon of the knee curve of measurable effect.

    It is very obvious that when you use insufficient tamping force such that proper cohesion of the coffee particles does not occur, then water under pressure will find the easiest path and result in non-uniform extraction throughout, creating less than optimum results in the cup. This is easily observable when a decent pressure gauge is used to monitor pressure at the Group Handle while producing an espresso. The pressure is never constant, even if the gauge fitted to the machine appears to be so, since its pressure source is quite often a considerable distance upstream of the Group Head and not indicative of what s going on in the coffee puck.

    Anyway, the thing to take away from this, is that one should aim to achieve consistently cohesive pucks that present, in themselves, the same resistance to water flow each and every time you pull a shot. This of course assumes that dose and distribution is identical for every espresso shot as well but this is something for another discussion...

    Mal.

  18. #18
    Senior Member trentski's Avatar
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    Re: Grinds

    Quote Originally Posted by 0601050D0106010D090C19600 link=1301871652/15#15 date=1302091680
    Quote Originally Posted by 41474A534B475F260 link=1301871652/14#14 date=1302088206
    now I dose at around 14g and tamp at about 15lbs as I prefer the flavours I am getting.
    Do you all pull only double shots? Because I do singles, is that ill-advised?


    Trentski,
    they are Haiti Komet from Giamaica Caffè, Verona, Italy, normal dark brown. I buy 10 kg at a time so it goes from 2 or 3 weeks since they were roasted to 2 or 3 months. But they are kept vacuum packed and in a refrigerator all the time.
    ;D got a little off topic there

    The single baskets are more difficult to use than doubles. So much so that when people make a single they use the double basket and only allow one stream to go into the cup, sometimes wasting the other to the drip tray or collecting it to freeze and use for iced coffee.

    Where abouts do you live? Is it possible to get beans locally so they are always fresh, or even roast your own? Generally speaking beans are past there best at the most 4 weeks after roasting.
    You would have noticed that when fresh the beans give much different results than they do after a couple of months, even when frozen.
    It may also be the case that the beans just taste like that and a better blend may suit you better.

    Other than that go back to basics.
    Keep your dosing and tamp consistent, alter the grind to get the 60mls in 30 seconds or there abouts (talking about doubles because it is easier).
    Dont over or underfill the basket, try the 5 cent peice trick.
    Only grind enough for the shot you are pulling, dont fill the hopper.
    Start counting as soon as you start brewing, not from when you first see the espresso, this could take up to 8 seconds with an E61.
    makes sure you let the machine warm up for at least half an hour.

    Practice

    Let us know how you go. Out of interest what E61 machine do you have?



  19. #19
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    Re: Grinds

    Quote Originally Posted by 7375626973746C6E070 link=1301871652/17#17 date=1302137274
    The single baskets are more difficult to use than doubles. So much so that when people make a single they use the double basket and only allow one stream to go into the cup, sometimes wasting the other to the drip tray or collecting it to freeze and use for iced coffee.
    It makes me wince seeing good coffee go into the drip tray.

    Ive been using by double basket for single shots on my sunbeam 4800. I dont like wasting good coffee but I do I up the dose to about 10-11g ( I measure 1+1/2 sunbeam spoons of whole beans, Im not sure the actual weight) and I dial the grind a bit finer so it takes about the same time to come through as if I was doing a double.

    Conan

  20. #20
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    Re: Grinds

    I should add Im using modified baskets that are now unpressurised. I guess that makes them depressurised.

    Does anybody else make a single shot in a double basket?

  21. #21
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    Re: Grinds

    Quote Originally Posted by 7478797679397875657E7279170 link=1301871652/19#19 date=1302151493
    Does anybody else make a single shot in a double basket?
    I wouldnt go that far. Id make a ristretto shot from a full double (~45mL) but probably wouldnt stop it at 30mL.

    If I have noone to share my double with, I generally just use my larger (160mL) cup and put a double in that.

    If I did try to get 30mL in 30 seconds from a full double basket, my machine would just reroute the water back through the OPV and it would choke.

  22. #22
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    Re: Grinds

    Quote Originally Posted by 7375626973746C6E070 link=1301871652/17#17 date=1302137274
    Where abouts do you live? Is it possible to get beans locally so they are always fresh, or even roast your own? Generally speaking beans are past there best at the most 4 weeks after roasting.
    You would have noticed that when fresh the beans give much different results than they do after a couple of months, even when frozen.
    It may also be the case that the beans just taste like that and a better blend may suit you better.

    Other than that go back to basics.
    Keep your dosing and tamp consistent, alter the grind to get the 60mls in 30 seconds or there abouts (talking about doubles because it is easier).
    Dont over or underfill the basket, try the 5 cent peice trick.
    Only grind enough for the shot you are pulling, dont fill the hopper.
    Start counting as soon as you start brewing, not from when you first see the espresso, this could take up to 8 seconds with an E61.
    makes sure you let the machine warm up for at least half an hour.

    Practice

    Let us know how you go. Out of interest what E61 machine do you have?
    Thanks for the advice. The machine is a V4 made by Vitudurum, a small Swiss firm. Here are a couple pictures I took for you to see what my set-up looks like.






  23. #23
    Mal Dimal's Avatar
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    Re: Grinds

    Wow!

    Nice Setup, great looking coffee and beaut photos.... [smiley=thumbsup.gif]

    Mal.

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    Re: Grinds

    Behmor Brazen - $249 - Free Freight
    coffee looks great, nice set up :)



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