As charged powder and free ions pile onto the part, the voltage across the powder layer rises until the air in it breaks down. Small discharges then push particles away, stop further build and leave starburst craters and heavy orange peel after cure. It shows on second coats, heavy builds and high kV. Lower kV, current limiting, more gun distance and tribo guns reduce it.
Second coat is all starbursts, you're back ionizing, drop the micro-amps and back off a few inches.
If film stops building no matter how long you spray, suspect back ionization before blaming the powder.
Also heard as
- back ion
- electrostatic rejection
- starring
Related terms
Free ions
Charged air molecules from a corona electrode that never attach to powder but still land on the part.
kV
Kilovolts, the voltage setting on a corona gun that governs how hard it charges the powder.
Orange peel
A dimpled surface texture like the skin of an orange, the most common appearance complaint on powder.
Recoat
A second coat of powder over a cured first coat, used to fix rejects or build a multi-coat system.
Corona gun
A powder gun that charges particles with a high-voltage electrode at the tip, the most common gun type.