OK I admit it - I both settle the portafilter and tap with the tamper and polish not only that but I pat the coffee down and level it prior to tamping with a straight piece of stainless steel. OK I am a little bit Obsessive (I am a CoffeeSnob after all so it is to be expected). I don't get channelling and I get consistent results. I find that it works for me. By the way I use a dressed portafilter, I have never felt the need to go naked

I'm not a chemist but do have a background in mineral sample preparation for analysis, I attempted to draw parallels between prepping samples and coffee making quite some time ago (grind consistency in particular) the silence was deafening.
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