Jake_G wrote:If you were to do EY% for each particle size, you would find a gradient of high extraction yield for small particles to low extraction yield with large particles with the average EY% being close to the extraction yield of the average sized particles.
I think this is more a theoretical difference than a real one. It assumes each particle is isolated and getting the same water and flow exposure.
Here's my theory: Highly extracted particles reabsorb solubles, while poorly extracted ones continue extracting. With enough time and interaction between particles, extraction levels even out, so that only the overall grind size and pour times determine the overall extraction level. Moreover, we know perfectly well how to do a badly and unevenly extracted shot: Overstuffed basket, no head space, no preinfusion, and above all laminar, "espresso-porn" flow through the puck, so there is no sideways diffusion or interaction between particles. Finally, finishing the shot by some weight standard, rather than when the flow is clear, so that the bottom of the puck (which recharges with the solubles from the top) is less extracted than the top. Pretty much everything many of the people who pontificate about extaction think is good practice. This is why these posts contain so much nonsense. If you have laminar flow through the puck, and are not worried about fully extracting the bottom layers, the only way to salvage anything is to have ann Uebergrinder producing perfect particle sizes.
It's the espresso version of Laputa.