timo888 wrote:Challenging accepted wisdom is what it's all about, right? I would not want either of us to shut up.
OK, then please allow me the luxury of challenging accepted wisdom, and take this in the spirit in which it's being offered. I'm simply reporting what I've discovered.
timo888 wrote:And by light, I mean VERY VERY lightly.
Unless you want to visit and observe for yourself, you're gonna have to trust me on this. I tamped VERY VERY lightly.
timo888 wrote:An exceptionally light tamp compresses the top region less than a heavy tamp compresses the bottom region.
You might be right, but this is another statement that I'd like to see evidence for. In this case, I am merely stating conventional wisdom, e.g. Mark Prince's article on Tamping Science, Theory and Practice:
Second, and most crucial, they believed that in manual hand tamping, no matter how much pressure a person exerts on the top of the bed of ground coffee, by the time one gets down to the bottom third of the bed, almost all that pressure is eaten up, and the bottom portion of the formed puck is barely compacted any more by the tamping pressure.
A light tamp may well reduce the chance of fracturing the puck on the upstroke. I was just hoping someone had figured out a way to test this hypothesis. And if a light tamp works better with multiple pulls, how about no tamp at all?
timo888 wrote:With a very light tamp, "gross differences" between first and second pull become less pronounced.
Not necessarily true. In my (admittedly limited) testing, a light tamp made little difference. But the differences between pulls were dramatic, regardless of tamp pressure.
Not all lever machines are created equal, and many factors impact extraction. You've pointed this out a number of times. La Pavoni has a high volume pull, high enough for one complete pull to yield a normale or even a lungo brew ratio. That pretty much guarantees a badly overextracted second pull.
timo888 wrote:Updosing makes the latter stage extraction more like the early stage extraction.
Before responding (or performing any more experiments), I'd like a clarification of this statement.





