Wet sieve and dry sieve analysis

Wet and dry sieve analyses determine the proportion of non-dispersible material and particle size for products formulated as water-dispersible granules/powder. This ensures formulations do not clog application equipment and screens for particles small enough to be inhalation risks. The sample is poured through a shaken, tapped or brushed sieve, and the retained residue is weighed and reported as a percentage. In wet sieving, the sample is dispersed in water first, then the residue on the sieve is dried before weighing (in CIPAC MT 185 wet sieving, the limit is 2% on a 75µm sieve). Both techniques can use a stack of sieves of decreasing mesh size to establish proportions in each size band. CIPAC MT 170 (dry) and MT 185 (wet) are frequent regulatory requirements.