THE MECHANICS OF COATING SEEDS IN A SMALL ROTATING DRUM

The production of coated seeds with known and reproducible performance requires that the coating process be controlled and repeatable. The d esign and development of computer-controlled, laboratory-scaled seed c oating equipment and operational parameters for the coating of seeds w ith fine, particulate material (especially lime) are described. One of the most important variables found to affect coat quality is the degr ee of atomisation of the adhesive; two alternate systems of spraying a dhesive are described. Some of the other factors affecting the coating process investigated include the effect of pre-coating the drum, the speed of drum rotation, a range of adhesive types and concentrations, and the duration and frequency of spray bursts in relation to addition s of solids. The evaluation of the physical integrity of coated seeds is outlined and combined with other parameters to yield a coating inde x which indicates the physical quality of a particular batch of coated seed.