. There was a tendency for the average particles to be larger than the values measured by sieves (Table 2). A possi- ble explanation for this broad distribution might be attributed to the smaller particles adhering to the surface of the big ones. As the more sensitive particle size analyzer uses a disaggregation de- vice, it would be expected that the small particles would be de- tected. On the other hand, the detection of larger particles above the average size aperture size could be explained by particle shape shadow effect as the particles pass through the laser beam (Mühlenweg and Dan Hirleman, 1998). This could also explain the slight difference in particle size distribution (Fig. 1) between the larger fractions (600 and 710 lm). Another explanation for this finding could be attributed to the small difference in sieve size aperture of the sieves 710 and 800 lm, which was only 90 lm.