Painting is a messy business, and when paint is sprayed, the possibilities for mess making are multiplied. There is however an easily used technique for minimising the mess. The nozzle of the spray gun is connected to a source of voltage. When spraying starts, this voltage is passed to the paint droplets as they leave the nozzle. If the object to be painted is given an opposite charge, then the paint droplets will be attracted to this object – even hard to reach places.
The paint droplets, having the same charge, will all be repelled from each other, so the paint will tend to be evenly distributed. The amount of paint needed (and wasted) is minimised.
The technique is not restricted to paint spraying. The chemicals used in crop spaying are charged to repel each other and achieve more even spraying. It is not possible to oppositely charge the plants, but this doesn't matter as much. All the chemicals are eventually washed away whether or not they reach the plants first.