Back-ionization appears as "starring" on the precured surface and orange peel after curing. This appearance is caused by powder that literally jumps off the work piece, like a submerged beach ball popping out of the water when released. It disturbs all the powder particles near it, thereby creating a crater, or hole, in the powder. This occurs because of an excessive amount of like charges.
To compound this further, these particles are continuously bombarded with like-charged free ions as long as the spray gun high-voltage field is present. Once too many of these like-charged particles have built up, they spontaneously repel each other. If you want to see this happen, just keep spraying the same spot, and eventually little craters will appear. In a properly functioning system, visible back-ionization is caused by too much powder and/or too much charge. The key to reducing back-ionization is to understand what factors contribute to this reaction.