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  • Tamping pressure, does it matter?

    Tamping pressure is a subject frequently referred to in threads about tamper fit, baskets, various machines, or frequently when people are having extraction problems.

    I've been playing around with different weight tamping recently, in an effort to determine just how much affect it has on extraction, seems to me once you have established a grind setting and dose that provides a shot your satisfied with, the weight of tamp has a relatively minor part to play in the process.

    I've tried everything from very light (probably only a kilo or two) to gorilla weight 10 to 15 kg and points in between (using my normal 18 grams) and found very little difference in extraction quality or time.

    All of the above assumes grind is right, machine is correctly set up and the tamper fits the basket reasonably well.

    My process is to grind,dose, level dose by tapping sides of portafilter, tap PF on bench to settle grounds then tamp and polish, I now use minimum pressure, at a guess about 3 or 4 kg, yep the coffee is just as good as its ever been.

  • #2
    Having conducted similar (very unscientific) tests myself, I concur. I have also locked the portafilter and made the pull without tamping at all (intentionally - many times), apart from a very mucky screen there seems to be minimal difference in the pour or cupped result.

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    • #3
      I hardly notice a difference at home, but on the La San Marco 85E at church has a 55mm portafilter and to fit 18g it's super deep. I use the tamp as a fine tune adjustment there, if the steps on the grinder aren't quite right I'll go coarser and tamp harder and it works quite well.

      I've also heard it said you should tamp hard enough so that the first drops of water from the shower screen don't disturb the surface of the puck. Anyone know if that's true?

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      • #4
        (sigh) this one again.
        Michael Teahan at Charlotte SCAA: Used a single tamp to show nada of significance between 30lb (Schomer's "industry bible pressure") and 300lbs. Actual scientific experiment showing no difference between "no tamp, no voids" and 300lb (NOT a typo) tamp. He also stated that after 1/4" (about 6mm) of depth there was no difference at all.

        CoffeeGeek - Tamping Science, Theory and Practice, Part One aka "Tamping Science, Theory and Practice, Part One" is well worth a read.
        Amongst other gems, it states that the LM swift grinder tamps 1mm at a time at 8lbs pressure. "I asked why, and Blackwell went on to explain that during the development of the grinder, they initially set the continuous tamping device at 30 pounds of pressure, and found that they created solid bricks in the filter basket, no matter how coarse the grind was. They were a bit mystified by it all, but eventually figured out two elements were at work."


        I was actually taught about "progressive tamping" (not even given a name to me at the time) in 1979 on the basis that it can make a substantial difference to the time required to dial in a new setup (easier troubleshooting) plus the fact that a series of gentle tamps gives more consistent pressure than one hard final tamp (i.e. just like the LM Swift). We did 1mm at a time, boot camp style with a guy that missed his vocation of army Sergeant Major. FYI, it was not regarded as a new technique new back then. If you use a naked p/f, it also prevents spraying unless you are way off level on the first tamp.


        I have posted on this subject a few times in CS and it seems to boomerang back every year or so.

        TampIt

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        • #5
          Yelta - Aside from the fact that "tamp pressure" is a misnomer, I'm a firm believer that it's importance is massively overrated and that the thickness of the puck is a more directly relevant variable.

          For this reason, I have tamped to a fixed depth for several years now, at first just estimating by feeling the top of the tamp and basket, but more recently I made a "fixed depth" tamper (picture here). It's interesting to note this style of tamper seems to be popular now.

          Originally posted by TampIt View Post
          I was actually taught about "progressive tamping" (not even given a name to me at the time) in 1979 on the basis that it can make a substantial difference to the time required to dial in a new setup (easier troubleshooting) plus the fact that a series of gentle tamps gives more consistent pressure than one hard final tamp (i.e. just like the LM Swift). We did 1mm at a time, boot camp style with a guy that missed his vocation of army Sergeant Major. FYI, it was not regarded as a new technique new back then. If you use a naked p/f, it also prevents spraying unless you are way off level on the first tamp.


          I have posted on this subject a few times in CS and it seems to boomerang back every year or so.

          TampIt
          Then why don't you post a video? I can't see how it would be possible to dose in that manner and not disturb the coffee beneath when distributing the next layer.

          Doesn't pass the risk vs return test for me; just seems like more opportunities to make a mistake...

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