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Powder Coating Terms

Back Ionization

  • An excessive build up of charged powder particles which may limit further powder being deposited on the substrate.  The electrical charge on the surface layer may be reversed, repelling additional powder.

Bulk Density

  • Mass per unit of volume in powder form including the air trapped between particles

Cartridge Filter

  • A cylindrical filter unit used to separate over-sprayed powder from air for recovery and reuse

Corona Charge

  • The process of inducing a static electric charge on powder particles by passing the powder through an electrostatic field generated by a high voltage device.

Cure Schedule

  • The time/temperature relationship required to properly fuse a powder coating


  • A type of recovery unit using a centrifugal process to separate over-sprayed powder particles from air flow.


  • The process of moving the powder through the application equipment to the end product

Edge Coverage

  • ​A powder's ability to flow over, build and adhere to sharp corners, angles, and edges

Faraday Cage Effect

  • A condition that may exist on a substrate due to its geometric configuration that may inhibit the electrostatic deposition of powder particles at a specific localized area.

Film Formation

  • The forming of a continuous film by melting powder particles and fusing them together by the application of energy.


  • The process of suspending  the powder in a continuous stream of air giving it "Fluid" characteristics.  Used to facilitate transfer of the powder to the application device.


  • The melting and flow of individual  powder particles when heated to form a continuous film.


  • The reference point in an electrical circuit from which voltages are measured, a common return path for electric current, or a direct physical connection to the Earth.​

Impact Fusion

  • The combining of powder particles to form a solid mass during the delivery and application process.

Lower Explosive Limit (LEL)

  • The lower point for a range of concentrations of organic particles suspended in air which can be ignited  by a sufficient energy source.


  • Common unit of measurement of coating thickness.  25.4 μ (microns or micrometers) = 1 mil (one thousandth of an inch)

Particle Size

  • Average diameter of an individual, irregular powder particle


  • The process of removing non-deposited powder from the air prior to reclaiming it for reuse.

Spray Booth

  • A specially designed enclosure in which powders are introduced, contained and recovered during the coating process.

Surface Appearance

  • Generally refers to the smoothness and gloss of powder coating films and the presence and degree of surface defects.

System Utilization or System Efficiency

  • The combined efficiency of each component in the powder coating system resulting in total material usage compared to the amount of material entered into the system.

Transfer Efficiency

  • The ratio of the powder deposited on the work-piece compared to the amount of powder sprayed during a fixed time period.

Tribo Charging

  • Process of creating a static electrical charge on powder particles by creating friction between them and a non-conductive material.

Virgin Powder

  • Powder that has not been previously sprayed as opposed to reclaim powder.


  • A characteristic of electrostatic application for the powder to seek out and adhere to parts of sight of the delivery point.