Abstract: An improved method and apparatus for adding relatively small amounts of one or more liquid additives to powder coating composition where the liquid is sprayed onto granular or particulate components of the powder composition during mechanical mixing to blend the components before further homogenizing by a melt mixing process.

Abstract: A method and apparatus for measuring the transfer efficiency during the electrostatic spraying of a coating material (e.g. powder coating) is provided. The transfer efficiency can be measured during the test cycle rather than measuring an average transfer efficiency for an electrostatic spray cycle. A cycle may include the initial time when the substrate is "uncoated or clean" and an end point of the test when electrical insulating effects caused by accumulated powder on the substrate lead to a reduction in the transfer efficiency. The method uses computer based calculation software and a computer. The computer is connected to load cells that measure weight changes of a target substrate and a vessel containing the coating material to be sprayed.