Heinz J. Niessen

DISPERSIBILITY AND FRIABILITY OF WATER-DISPERSIBLE GRANULES

Abstract Water-dispersible granules (WG) are pesticide formulations that are almost free from dust and easy to handle. They are used in a manner similar to the known water-dispersible powders (WP). For their specification, the same criteria as for WPs must therefore be applied at first (e.g. suspensibility, wettability). However, in order to guarantee good product properties, additional parameters must therefore be measured. Methods for the quantitative determination of re-dispersibility in water and of friability are described. The measured data reveal distinct differences among various formulations, and demonstrate the need for using a mechanical sample divider for partitioning a gross laboratory sample into representative sub-samples. The fines of the product, likewise relevant to quality, are measured by known methods of dry sieving. A measurement of flowability should not be included in generally valid specifications.