If it is indeed volume %, two possibilities would be:

i) Preciso's setting of 8A isn't close to espresso grind - since the peak mean of the bigger particles is around 500um for Baratza's, whereas it's 300um for Socratic's.
ii) The mesh step size in Socratic's test is too huge - thus has limited resolution and missing the huge valley at 100-200um altogether.

Also, Socratic Coffee said that they didn't manage to observe sieved grind below 75um - that brings us to another limitation of sieving. Adhesion issue of fines to larger particles is pretty severe and there's no way currently to eliminate that without dispersing the fines in liquid. p/s: to plug my own thread, you can see the microscopic images of fines in this threads Note particularly how much fines were released once they're dispersed in the solvent. More interestingly, note that even laser diffraction technique hardly captures fines at 1-5 micron.

If we refer back to Titan Grinder Project: Particle size distributions of ground coffee then it's clear that different aspects of analysis vary between grinders and so knowing the parameters is important.

baldheadracing wrote:Doing science means using the scientific method: (10 minutes of one of the greatest physicists of the 20th century)

An even greater physicist, Albert Einstein, when asked what he would have said if Sir Arthur Eddington's observations of light bending had been inconsistent with the General Theory of Relativity, replied: "I would have been sorry for Eddington, because the theory is right."

Ah, the great old arguments between experimental and theoretical physicists... Einstein himself changed his theories many times, so let's not get too carried away with arguments to authorities.

This thread hasnt really gone anywhere since the first page, until there is evidence that supports the contention that sieves are an accurate and reliable way to measure coffee particle size distribution - there is no point in jumping ahead and trying to draw conclusions about what the data means.

+1

Truth.

galumay wrote:This thread hasnt really gone anywhere since the first page, until there is evidence that supports the contention that sieves are an accurate and reliable way to measure coffee particle size distribution - there is no point in jumping ahead and trying to draw conclusions about what the data means.

Actually, that was the implication I was getting at. If you consider the disparity between baratzas data and Socratic's, then the incredible similarity between all of the comsumer grinders and all the pro grinders it is obvious that this time it missed the mark.