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.

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.


A type of recovery unit using a centrifugal process to separate oversprayed powder particles from an air flow.

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.


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 electrical grounding of the item to be coated.

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.

Particle Size

Average diameter of an individual, irregular powder particle.

Spray Booth

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

System Utilization or System Efficiency

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

Tribo Charging

Process of creating a static electrical charge on powder particles by creating friction between them and a nonconductive material.

Cartridge Filter

A cylindrical filter unit used to separate oversprayed powder from air for recovery and reuse.

Cure Schedule

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


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

Electrostatic Spray Technique

A deposition method of spraying and charging powder so that it is deposited on a grounded substrate. (See Corona charging and Tribo charging.)

Film Formation

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


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

Impact Fusion

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


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


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

Surface Appearance

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

Transfer Efficiency

The ratio of the powder deposited on the workpiece compared to the amount of powder sprayed during a fixed time period.

Virgin Powder

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


A characteristic of electrostatic application for the powder to seek out and adhere to parts of the substrate not in direct line of sight of the delivery point.