Announcement

Collapse
No announcement yet.

Why tamping doesnt matter as much as you think

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Why tamping doesnt matter as much as you think

    The magical 15 kg of "force/pressure" has often been used as a benchmark for tamping in industry. It gives baristas a baseline to work from – 15 kg of downward "force" is merely a trade off between the compactness of the bed of coffee and preventing RSI (repetitive strain injury) for baristas tamping hundreds of group handles a day. As long as you are consistent, it does not matter how hard you tamp.

    The reasoning is this: tamping harder or softer will have negligible impact on an extraction flow rate once the coffee bed has been tamped with sufficient pressure to remove any air pockets between coffee grinds. 9 bar of extraction pressure is 16 times greater  than the pressure of a 15 kg tamp. Tamping pressure is immediately alleviated during the period when the dry coffee is wetted and once the extraction is in full swing will always be much less than pump pressure.

    So when someone says tamp harder to slow down an extraction, I call bs!  :

    Discuss, debate, theorise..... 8-)

  • #2
    Re: Why tamping doesnt matter as much as you think

    Originally posted by 0E383B392E3838241828232424274B0 link=1332222307/0#0 date=1332222307
    So when someone says tamp harder to slow down an extraction, I call bs!
    Two thought provoking posts back to back! Thanks Dave.  8-)

    Yep- I totally agree. In fact its amazing to look at how bad a tamp can be and yet still be normalised by the machine (given correct dose). This will be a debate well worth reading!

    Chris

    Comment


    • #3
      Re: Why tamping doesnt matter as much as you think

      I think its a give and take.

      If youre not going to tamp hard, then its better if you use more coffee and/or a finer grind. Conversely If you are going to tamp as hard as you can, then its better if you use less coffee and/or coarser grind.

      I use to tamp pretty hard because a domestic course I did a few years back (2006 at Danes / the gourmet coffee institute) said 15kg was the sweet spot. I knew the trainer and he made great coffee and won competitions etc.  so I naturally took this on board.

      It wasn’t until last year I made some changes to how I make coffee. The owner of the cafe invited me behind the counter and watched me make my coffee. He commented on the amount of pressure I used to tamp, and recommended that I grind finer and use less force. He also said it wasn’t important to have a dry and rock hard puck once the extraction was finished (which is something I also use to aim for – I was told it should have an imprint of the shower screen).

      Both Baristas make an excellent cup of coffee and yet both have different techniques. It just goes to show that either way works.

      I’ve gone for the middle ground and use 3~5kgs (maybe even less!) of force. My pucks now have a slight imprint of the shower screen and hold their shape when knocked out. They are somewhat firm, but not rock hard as they use to be.

      Comment


      • #4
        Re: Why tamping doesnt matter as much as you think

        Originally posted by 1310050309010C10010E1413600 link=1332222307/2#2 date=1332237329
        My pucks now have a slight imprint of the shower screen and hold their shape when knocked out. They are somewhat firm, but not rock hard as they use to be.
        To the uninitiated this could really read like a health forum.
        Cheers
        BOSW

        Comment


        • #5
          Re: Why tamping doesnt matter as much as you think

          Since getting the duetto and kony ive played around alot more with different techniques. What I have found though is if I get the dose weight right (vst 18g basket) i dont have to worry about tamping pressure, i just polish and extract. I have compared this to a 15kg tamp same dose and grind and extraction is the same.

          I think Ive seen a Scott C you tube video where he explains this, though it may have been someone else sorry.

          Comment


          • #6
            Re: Why tamping doesnt matter as much as you think

            Espresso School,
            Have you ever tried an experiment where you try changing only the tamping weight?
            I have and it makes a huge difference. You can vary from a restricted pour to a fast pour at the extremes.

            I expect a consistent grind / tamp is what is important, grind fine and tamp light or vice versa.

            Lee

            Comment


            • #7
              Re: Why tamping doesnt matter as much as you think

              Originally posted by 2E2F212E2330272C420 link=1332222307/5#5 date=1332240229
              Espresso School,
              Have you ever tried an experiment where you try changing only the tamping weight?
              I have and it makes a huge difference. You can vary from a restricted pour to a fast pour at the extremes.

              I disagree. Tamp can effect pour time but the amount of variation is negligable compared to grind. As others have said, I dont think dose can be underestimated either.

              I tend to think that a level tamp is more important than the actual pressure used. What do you guys reckon?

              Comment


              • #8
                Re: Why tamping doesnt matter as much as you think

                "I tend to think that a level tamp is more important than the actual pressure used. What do you guys reckon?"

                I agree level tamp, dose and grind size seem to be what has the greatest effect on the results for me.

                Comment


                • #9
                  Re: Why tamping doesnt matter as much as you think

                  Heres another variable: preinfusion

                  Without preinfusion my tamp does seem to matter a bit more, tamp too light and I occasionally get some chanelling. Tamping firmly fixes it.
                  With pre-infusion, tamp pressure makes a lot less of a difference, as long as its distributed evenly.

                  Comment


                  • #10
                    Re: Why tamping doesnt matter as much as you think

                    Originally posted by 55545A55584B5C57390 link=1332222307/5#5 date=1332240229
                    Espresso School,
                    Have you ever tried an experiment where you try changing only the tamping weight?
                    I have and it makes a huge difference. You can vary from a restricted pour to a fast pour at the extremes.

                    I expect a consistent grind / tamp is what is important, grind fine and tamp light or vice versa.

                    Lee
                    Hi Lee,

                    Originally posted by 7C4A494B5C4A4A566A5A51565655390 link=1332222307/0#0 date=1332222307
                    The reasoning is this: tamping harder or softer will have negligible impact on an extraction flow rate once the coffee bed has been tamped with sufficient pressure to remove any air pockets between coffee grinds....Tamping pressure is immediately alleviated during the period when the dry coffee is wetted and once the extraction is in full swing will always be much less than pump pressure.
                    So in summary, if you tamp like a gorilla, its going to have negligible effect on the overall extraction. What you will do though is cause the infusion time to be longer by a few seconds at most. The key thing here is that you have tamped sufficiently hard enough to remove any pockets of air between grinds.


                    Good discussion so far! 8-)

                    Comment


                    • #11
                      Re: Why tamping doesnt matter as much as you think

                      Heres the mathematics behind it all.





                      Assuming a 15 kg tamp.



                      We know an espresso machine pump operates typically at 9 bar.

                      0.56 bar of tamping pressure is dwarfed by 9 bar of pump/brewing pressure. To put it in simpler terms, pump pressure is 16 times greater than the pressure of a 15 kg tamp in a 58 mm filter basket!

                      Comment


                      • #12
                        Re: Why tamping doesnt matter as much as you think

                        One problem with that analysis. You are assuming that the pressure drop over your puck is the full 9 bar. I dont think that will be the case. Most of the pressure will likely be dissipated once the water passes through the puck.

                        The actual pressure drop over the puck depends on lots of factors (particle size, void space, particle surface properties, fluid viscosity...) and would be very hard to calculate (and it would be hard to make reasonable assumptions of those factors).

                        I think it would be more relevant to consider/discuss what happens to the puck when wetted, and whether this varies depending on tamp pressure (which will tell you if dP over the puck will vary depending on tamp pressure).

                        My 2c.

                        Comment


                        • #13
                          Re: Why tamping doesnt matter as much as you think

                          If you find that a very hard tamp or a very light tamp is necessary, you are most likely compensating for some other problem which should be addressed.

                          What force to use? Just tamp hard without getting crazy about it. Anything from about 14-16Kg (30-35 pounds) and up will do fine. You can test that using a scale. You should find that once you hit that level of force that there is virtually no compacting of the coffee as you increase the force.

                          Consistency is important, but anything between about 14-27Kg (30-60 pounds) will be fine.

                          As far as comparing water force to the force applied to your tamper, this is apples and oranges unless the water is in the form of ice. Water delivery at the beginning of the extraction is not applied evenly, and water is a solvent. Depending on how the pressure is applied (slow infusion as from an E-61 or rudely as in a Silvia) can do all sorts of things to the coffee that make this comparison not very accurate at all.. IMO.

                          Tamp level, tamp with a consistent force, use a proper-fitting tamper, and never tap the sides of the portafilter after tamping. Beyond that, dont worry about it.

                          Comment


                          • #14
                            Re: Why tamping doesnt matter as much as you think

                            Originally posted by 112724263127273B07373C3B3B38540 link=1332222307/0#0 date=1332222307
                            So when someone says tamp harder to slow down an extraction, I call bs! 
                            I suspect that applying a simplistic, quasi-scientific analysis to the process has led to this assumption.

                            Its certainly not as simple as comparing the force applied by the pump with the force of the tamping.

                            Empirically, I know I can compensate for minor differences in the grinder setting with minor changes in the tamp pressure. I have an adjustable, clicking tamper so I know exactly what tamp pressure I am applying and I use a spring lever machine so application of pressure is gentle and consistent.

                            As an example if I am making a few coffees and the grind is a little bit fine, i will back off the adjustable tamper slightly and I will see a direct increase in flow rate of the pour - and vice versa if its a bit coarse.

                            I will choose to adjust the tamp rather than the grind if I am in a hurry and using the Pharos as its a bit quicker to adjust the tamper.

                            Originally posted by 06353A302D0B137A540 link=1332222307/12#12 date=1332265122
                            Tamp level, tamp with a consistent force, use a proper-fitting tamper, and never tap the sides of the portafilter after tamping. Beyond that, dont worry about it.
                            Exactly!

                            Comment


                            • #15
                              Re: Why tamping doesnt matter as much as you think

                              Ive had varying feedback on this subject (and that of fitted tampers) over the years. I put it down to different machines. Maybe its pre-infusion, not sure. But certainly low to mid-end machines seem to give much worse results with a loose tamper or no tamper at all, compared to top-end machines. Tamp pressure would be a subset of this argument. Thats of course overlooking the mess factor that has to be cleaned up by not tamping and the problems if you dont clean it up.

                              Greg

                              Comment

                              Working...
                              X