The Tribo process is based on frictional charging. In this case, the fluidised powder/air mixture in a powder tube, usually PTFE, is charged by means of friction against the inside tube wall. Due to its excellent electrical insulation properties (negative), PTFE is well-suited to charging the particles and its good anti-frictional properties prevent sintering on the walls. Frictional charging in the powder tube generates a uniform charge and charge separation. This means that for a certain quantity of positively charged powder particles, the same number of negatively charged particles remain in the powder tube. This negative charge must be conveyed out of the spray device. It is conducted via a measurement sensor and, as a Tribo current, provides information on the quality of the powder and the charge. Because of the frictional charging, this procedure requires special Trbo powder. In WAGNER Tribo guns, the charge can be influenced and magnified by means of a special Tribo air supply. In this way, for example, even powder that is resistant to charging can still be applied.