GB/T 5211.18-2015 "General methods of test for pigments and extenders - Part 18: Determination of residue on sieve - Water method (manual procedure)" specifies a general manual water method for determining the residue on sieve of pigments and extenders, applicable to the residue testing of most such products. The test requires equipment such as test sieves meeting the requirements of GB/T 6005 (typically with a 45μm aperture), a bristle brush, a glass filter, an oven at (105±2)°C, balances with accuracies of 0.1g and 1mg respectively, and a mechanical stirrer. By dispersing the sample in water, followed by sieving, washing, drying, and weighing, the mass fraction of the residue on sieve is calculated. The test results must specify the instrument parameters and operational details used, providing technical reference for particle size control in pigment products.