Beginner's Powder Coating Glossary

Abrasive: A coarse material used in blasting. Materials include sand, steel shot, glass beads and plastics.

Additive: Chemicals added to powder coatings to improve some properties, such as flow, gloss, and texture control.

Adhesion: The powders bonding strength, the ability to attach to a material by means of surface attraction.

Air Velocity: The measurement of air speed, in feet per minute.

Air Volume: The amount of air needed to transport and apply powder particles in a coating system, measured in cubic feet per minute (CFM).

Ambient: Surrounding environmental conditions.

Application: The process of applying a coating to a substrate.

Arcing: The discharge of built-up electrical charge, usually producing a spark to an item of lower charge.

Atomizing Air: Air added into the powder path to atomize it into a pattern.

Back Ionisation: Excessive build up of charged powder particles that limit powder to be deposited onto the substrate.

Blistering: Bubbles formed under a cured powder film, usually caused by the expansion of trapped air, moisture, or corrosion, either in a coating or in the substrate.

Cartridge Booth: A type of recovery booth that uses a cartridge filter system to collect oversprayed powder.

CFM: Cubic Feet per Minute. Volume movement of a fluid. A measure used to size powder systems based on captive air. If not otherwise defined, the conditions are presumed to be air at a temperature of 68 degrees F, a pressure of 14.70 pounds per cubic foot. In gas industries, the temperature of standard air is usually given at 60 degrees F.

Clearcoat: Non-pigmented coating.

Contaminants: Materials like dirt, dust or oil that effect the finish of the cured powder film

Corona: Ionised air formed by a discharge of electricity.

Corona charging: The process of using a static electric charge from a multiplier on the powder particles to cause the powder to adhere to the grounded substrate.

Cratering: Small round depressions in a powder film.

Cross Hatch: A test to determine adhesion.

Cyclone: A cylindrical that separates powder particles from the air.

Deflector: Conical shaped disc attached to the end of the powder gun to distribute the powder in circular pattern.

Electrode: The device at the end of the spray gun that create air ions at high voltage to produce a charge for the particles.

Electrostatic Fluid Bed: The fluid bed has an electrode grid to charge the powder so that it will coat ground items put in the bed.

Etching: Surface treatment of a metal before chemical process.

Fan Pattern: Shape of the cloud exiting the gun.

Faraday cage effect: A condition that may exist on a substrate due to its geometric configuration that may inhibit the electrostatic application of powder particles at that specific localized area, such as corners, cavities or recesses.

Ferrous: Contains iron.

Film thickness: Depth of cured coatings, measured in microns or inch.

Fines: Small powder particles. Usually under 10 microns.

Fish Eyes: A large surface depression in a coating film. Can be caused by oil or silicone.

Flow: Powder coatings naturally want to  level into a uniform mill thickness.

Fluidized: When powder is in a state of suspension using compressed air to make a fluidize mixture of powder and air.

FPM: Feet per minute. A measure of air flow speed.

Galvanized Steel: Steel coated with a layer of zinc.

Gassing: Air or gas that escapes from the sub surface beneath a coating and causes blisters, eruptions or bubbles in the coating.

Geysers: Uneven mixture of air and powder that cause the fluidized powder to not look like a calm surface.

Gloss: The degree of reflection of light from the cured film.

Grounding: Grounding is critical when it comes to the powder coating process. It enables the efficient transfer of the electrostatic charge between the powder gun and the substrate. Grounding rods must be used and placed at a depth of at least 8 feet.

Hepa filter: High efficiency particulate air filter.  Hepa filters should be able remove at least 99.97% of dust, pollen, mold, or any particle that is at least 0.3 microns in size. Powder final filters often are only as efficient as 95%.

Hybrid: A mixture of epoxy and polyester powder product.

Impact Fusion: When the powder sticks to and builds up on the interior of application equipment. The guns and venturi pumps are most susceptible. 

Infrared Oven: Ovens using infrered rely on radiation to heat the surface of the powder coated object.

Iron Phosphating: This chemical treatment protects steel from corrosion and improved adhesion.

MSDS: Material safety data sheet. Information listing all known hazardous ingredients, health hazards, first-aid procedures and protective equipment necessary for the product being used.

Masking: Covering an area of a part to prevent the powder from coating where it is not wanted.

Mill: A unit of measure for the thickness in powder.  One thousandth of an inch (0.001”).

MSDS: Material Safety Data Sheet.

Melting Point: The temperature at which a finely divided powder will begin to melt and flow.

Non-ferrous: A material containing no iron.

Orange Peel: An appearance of uneven or rough surface that sometimes resembles an orange peel, that is caused by the flow characteristics.

Oscillator: A device for moving automatic guns in a vertical plane to provide uniform and increased powder coverage.

Outgassing: Is the release of a gas or air that was dissolved, trapped, or absorbed in a material.  Powder coaters may face specific issues related to outgassing when working with porous metal substrates like iron, steel and aluminum. Gasses and impurities must be released prior to powder coating.

Oven: The enclosed area that cures the powder by heat or infrared.

Overbake: Over cooking either by leaving the product in the oven to long, or a temperature higher than what the powder manufacture recommends. This will result discoloration, loss of gloss, or to much gloss on flat powders.

Overspray: The powder that does not deposit on the product intended to be coated. This will result in more powder going to waste or the recovery system.

Particle Size: The average diameter of the particle in the powder.

Pigment: Particles in a powder coating formulation that provides the color, or other desired effect.

Pinholes: Small holes on the surface that form at the substrate. It has the appearance of small craters on the cured product.

Pressure Drop: Loss in pressure often due to the length and/or diameter of the delivery hose. Filters that are blocked can also cause pressure drop.

Preheat: Heating the part prior to applying the powder coating.

Pre-treatment: The preparation of a part prior to the coating to improve adhesion and corrosion resistance.

Purging: Cleaning out any remaining powder from all parts of the powder equipment that come in contact with the powder prior to starting a new color.

Reciprocator: A device that moves the automatic guns to allow for more coverage per gun.

Reclaim: Taking over sprayed powder and reuse it after sieving and adding virgin powder.

Recovery system: A filtration system that contains over sprayed powder so that it does not leave the booth area.

Rework: The process to correct imperfections or defects.

Runs: When the powder has the appearance of drooping or sagging. This occurs if the powder is applied heavily, or onto a hot surface.

Sand blasting: The process of removing corrosion by the impact of spraying sand or another abrasive material.

Sieve: A device, either in line, or standalone that sifts out contaminants from recycled powder. Different screen meshes can be used to determine how much is removed from the collected powder.

Spray pattern: The configuration of the spray leaving the powder gun.

Substrate: The part that is being coated with powder.

Surge: A sudden burst of powder from the spray gun.

Tape Adhesion: Test used to check for adhesion of a coating to the surface of the substrate.

Tensile strength: A measurement defined as the stress as a force per unit cross sectional area, required to break it.

Thermal barrier: A coating that is designed to insulate the substrate from heat.

Transfer efficiency: The ratio of the powder deposited compared to the amount directed at the part to be coated.

Tribocharging: The process of statically charging the powder by friction instead of a KV gun.

Under cured: When the coated product has not been sufficiently heated and/or spent enough time in the oven.

UV flame detection system: A system that senses the UV light emission caused by an ignition source. In powder coating application systems these devices are used to shut down the spray process when a spark is detected.

Venturi effect: The process of using a venturi pump with a narrow opening that increases the velocity to transport the powder from the hopper to the spray gun.

Vibratory box feeder: A device allowing the powder to be pumped directly from the box of powder using both vibration and a powder down tube that has air added at the tube.

Virgin powder: Powder that has not been used, or collected through the recovery system.

Voltage tester: An instrument that measures the voltage output at the end of the electrostatic spray gun.

Waggler: Similar to an oscillator, but the guns are on a pivot instead of an elevator.

Wrap: The ability of the electrostatic charged powder to adhere to the products sides that are not in front of the gun.