The procedure includes weighing out a test portion of approximately 300 g of the sample, placing the test portion in the top sieve of a set of test sieves (including all the sieves listed against the grade under test in the appropriate part of ISO 11126) with the largest-aperture sieve on the top and progress to the smallest aperture at the bottom with a pan, to catch any abrasive that falls through the finest sieve, sieving in a sieve machine, weighing the abrasive retained on each sieve and transferred on to a balance pan. Annex A gives information on the international standards series for non-metallic blast-cleaning abrasives ISO 11126 and ISO 11127.