What is a Mid-Point Sieve?


The Endecotts' inspection process for sieves

The inspection process for all Endecotts certified sieves is stringent to ensure only World Class Quality Sieves are produced. Every roll of wire cloth received by Endecotts is given an initial visual inspection. The cloth is stretched out over a back lit table and inspected for defects in the weave. Then, the accepted cloth is cut into three, eight and twelve inch squares and goes through a more thorough visual inspection using an optical comparitor. Next, the frame, skirt, and fillet are added to the mesh squares that pass the optical examination. Once the sieve is constructed, its inner and outer diameters are inspected against traceable gauges. If the sieve passes inspection, it returns to the optical comparitor again. The comparitor prints a sieve certificate or rejection form after it has finished scanning the sieve. During the final inspection, up to 30% of the sieves are rejected and destroyed by Endecotts.

The Endecotts' inspection for Mid-Point Sieves

The increasing demand for more precise and accurate sieve analyses led Endecotts to develop a method to select a premium quality sieve. MidPoint Sieves are manufactured to tolerances that have been reduced by 30%, in comparison to ASTM E-11 specifications. This results in sieves that fall in the middle of the ASTM E-11 tolerance range, providing precise and accurate testing.

For an example of how the MidPoint Sieve specifications compare to the ASTM E11 specifications, the tolerances for a #18 (1.00 mm) sieve will be used.

Y , +Y



Y : Permissible variation of average opening from standard sieve designation (standard deviation allowed for aperture size)
X : Value of maximum individual openin
Z : Value of intermediate tolerance

How are Mid-Point Sieves Used?

Endecotts Mid-Point sieves were developed in order to meet the rising demand for precision and accuracy when using matched sets and also for an easy calibration technique for working test sieves.


Many of our customers demand precise particle size analyses that even certified sieves cannot provide. The mesh used when manufacturing Mid-Point sieves have aperture sizes in the middle of ASTM E-11 tolerance range specifications. The reduced tolerance range used during Mid-Point sieve production ensures consistent and accurate results.

Calibration of your Working Test Sieves

When we developed the calibration procedure using Mid-Point sieves, our goal was to provide an easy and inexpensive way to calibrate working test sieves. More information is provided in the CSC Scientific article How to Calibrate Working Test Sieves.

Matched Sieve Sets

Many of our customers have found they prefer using Mid-Point sieves in place of traditional Matched Sets for two reasons: the availability of Mid-Point sieves and the reliability of the results that are provided using Mid-Points. A Matched Set is obtained using all Mid-Point sieves for a designated stack. Because all Mid-Point sieves are certified and inspected to the same range of tolerances, not by using a sample standard, results are accurate and precise for every stack of sieves you use. Mid-Point sieves are also readily available, so you will not have to wait for a replacement sieve.