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When preforming a grain size distribution on a sample of Soil using Mechanical Sieves (e.g. Sieve #4 and sieve #10 and sieve #40) one of the necessary calculation need for drawing the particle size distribution curve is the Cumulative Passing percentage of Soil Particles (aka Percent Finer).

The formulas are pretty straight forward, but what is the physical meaning of Percent Finer? What does it imply ?

Here is a reference table:

Calculation Sheet

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Percent finer is the amount of material from a sample that is smaller than a certain size.

On the example table provided, the Sieve No. 12 (150 micron) has a % finer of 18.2%. This means that 18.2% of the material passed through that sieve, and 81.8% (which is 100% - 18.2%, which you can see in the "Cumulative Retained" column) was "caught", or retained, by that sieve.

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"% Finer" represents the percentage of material of the total sample (100%) that will pass through the current sieve.

Or if you want to express it the other way round: 100% - "% Finer" = "% Retained cumulatively" This will represent the cumulative material retained of all sieves with a larger aperture as well as the current sieve.

Colloquially one could compare it to a single sieve in a flour mill when separating the proverbial wheat from the chaff. The "% Finer" being the wheat and the the "% Retained cumulatively" being the chaff.

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