spencerwebb wrote:I tried sieving espresso grinds with a home-made 125 micron sieve, I didn't even manage to get 0.01g of fines in a couple of minutes of shaking.
There may be about 0.3 grams sub 125 micron fines in a double shot of espresso, at least according to the laser particle counters. To get all that you'll need a shaker, since the fines clump tightly into the nooks and crannies in the coarse ground particles.
But unless you happen to be a bloodhound or the princess on a pea, I don't see much point -- the amount of fines is too small to affect the taste. The taste differences people get by sieving ground coffee are those that Robert observed, due not the missing fines, but by compensating for their absence with coarse particles that are ground finer.
But Robert's observations also show there is a missing piece of knowledge here -- how much of the flow control in an espresso puck comes from the fines (i.e. the sub 100 micron particles), and how much comes from the heterogeneity of the coarse particles (150 - 1000 microns), i.e. from their absolute size differences along with their shape differences