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Glossary of Terms

Powder Coating Terms & Definitions
(A - E)
                F    G    H    I   L    M   N    O                  (P - S)                    (T - Z)

Fading - Gradual loss of color of a paint film due to a chemical or physical change, usually caused by ultraviolet light.

Fan Pattern - Geometry or shape of spray pattern.

Fan Spray Nozzle - A powder gun tip that provides a fan-shaped spray pattern.

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 cavities or recesses.

Fatty Edge - Thick film sometimes found on heavily coated work, resulting in a rounded, thicker film along the edges.

Feed Hopper - A container that holds powder for supply to the guns. Most feed hopper designs employ fluidization of the powder for uniform feed to the guns. See Fluidized Bed.

Ferrous - Containing iron.

Filler - Extender, bulking agent or inert pigment.

Film Build - Cured thickness characteristics of the coatings.

Film Thickness - Depth of cured coating, usually expressed in mils, 1/1,000 of an inch.

Fines - Small powder particles, usually under 10 microns.

Fisheye - A large surface depression in a coating film often caused by a contaminant such as oil or silicone.

Flash Rusting - Very thin film of rust occurring within minutes after applying a pretreatment solution.

Flow - Measure of self-leveling. Characteristics of a coating allowing it to level or spread into a smooth film of uniform thickness before hardening. 

Fluidize - A term that describes powder that is in a state of suspension using compressed air, creating a fluid mixture of air and powder.

Fluidized Bed - A fixed container in which powder is suspended in a continuous stream of air. Preheated objects may be coated by dipping directly into a fluidized bed. The fluidized bed may also be used to facilitate transfer of powder materials to an alternate application site.

FPM - Feet Per Minute, a measure of air flow speed.

Galvanized Steel - Steel coated with a layer of metallic zinc.

Gassing - Air or gas that escapes from a sub-surface beneath a coating and causes blisters, bubbles or small holes in the coating. Gassing frequently occurs with zinc or aluminum castings or galvanized steel and is commonly referred to as out-gassing.

Gauge - Instrument or device for measuring, indicating or comparing a physical characteristic.

Gel Time - Interval required at a given temperature for a powder to be transformed from a dry solid to a gel-like state. Gel time is measured in seconds at a given temperature.

Geysers - Spouts of air and powder found in a fluid hopper when uneven air dispersion is applied.

Gloss - The degree to which a surface reflects light. Light striking a surface causes a portion of the light to bounce off the surface which is gloss, and the other portion of the light penetrates into the surface, where part of it is absorbed and then refracted and reflected. High gloss surfaces are typically very shiny.

Gloss Retention - Ability to retain the original gloss.

GPM - Gallons Per Minute.

Grounding - A method of removing or adding electrical charge.

Gun Extension - Extension adapter to a spray gun. Allows for better penetration for manual reinforcement.

Hardener - Curing agent for thermoset powder formulations.

Hardness - The ability of a cured coating to withstand indentation.

HEPA Filter - High efficiency particulate air-purifying filter. Separates particles down to sub-micron sizes from air.

Hexavalent Chrome - Chromium most often used as a seal rinse in a five- or more stage pretreatment system. Has a +6 valence Hex and is considered a reactive seal rinse.

Hiding Power - The extent to which a powder coating masks the color and pattern of the surface it is applied to at a given film thickness.

HVAC - Heating, Ventilating, Air Conditioning air supply system.

Hybrid - An epoxy-modified polyester or an epoxy-modified acrylic thermoset coating powder. Hybrids usually have good overbake and good application properties.

Hygroscopic - The tendency of a substance to attract or absorb moisture from the air.

Impact Fusion - The tendency of finely divided powders to combine with other particles in the application equipment during the application process.

Infrared Radiation - Electromagnetic energy in the infrared region of the electromagnetic spectrum.

Integral Charging - A powder gun that has a low voltage signal supplied to it and steps up the current to high voltage via a cascade multiplier located in the gun barrel.

Intercoat Adhesion - A coating powder's ability to adhere to previously applied films.

Iron Phosphate - Conversion coating. Chemical deposition on steel and aluminum for corrosion protection.

Isocyanate Resins - Urethane resins. Isocyanate curing agent which when heated or reacted with hydroxyl functional polymers, give urethane coatings.

Lance Extension - Variable extensions for powder guns.

Lower Explosive Limit (LEL) - The lower point for a range of concentrations or organic particles suspended in air which can be ignited by a sufficient energy source. Also referred to MEC or Minimum Explosive Concentration.

Magnehelic Gauge - Trade name of Dwyer Instruments' gauge for measuring air pressure in inches or water column.

Mandrel Bend Test - Physical bending test for testing flexibility. (ASTM Test D522)

Masking - Covering areas of a part to prevent coverage by powder during application.

Material Safety Data Sheet (MSDS) - Information supplied by coating manufacturers listing all known hazardous ingredients, physical and health hazards, first-aid procedures and protective equipment.

Material Utilization - The percentage of a volume of powder that actually is deposited on the parts, not lost through handling, transfer onto the racks, contamination or as non-reclaimed powder.

Matte - A surface with minimal reflection of light, the opposite of high gloss.

Melt Mixing - A predominant process for the manufacture of coating powders involving the continuous compounding of the pigments, fillers, catalysts and resins at elevated temperatures.

Mil - A measurement of film thickness, 1 mil = .001'.

Mild Steel - Structural steel or plate, malleable iron based alloy. SAE 1020, with a carbon content of up to 2.5%.

Mileage - Term used to describe the amount of area that can be covered with a given amount of coating material. Measured in ft2/lb.

Mill Scale - Oxide layer formed on steel by hot rolling process.

Molten Salt - Inorganic chemical or chemicals that are used at temperatures above their melting point as heat transfer, heat treating or metal cleaning purposes.

Molten Salt Bath - A specially designed vessel used to contain and heat molten salt processes.

National Fire Protection Association (NFPA) - An organization that has developed a system for indicating the health, flammability and re-activity hazards of chemicals.

Non-Ferrous - A material containing no iron.

Nylon - A thermoplastic powder coating which contains long-chain polymers consisting of recurring amide groups (CONH). These coatings are tough, abrasion-resistant and exhibit good chemical resistance.

OEM - Original Equipment Manufacturer.

Off-color - Not matching the color standard to which the coating is being compared.

Ohm - A unit of electrical resistance.

Opacity - Ability to hide the substrate of a given film thickness.

Orange Peel - A wavy irregularity in the surface of a paint film coated by the flow characteristics of the coating. Orange peel appears as a characteristically uneven or rough surface to the eye, but usually feels smooth to the touch.

Organic - Substance containing carbon compounds.

Organic Powder - That which was derived from carbon atoms containing compounds such as epoxies, polyesters, hybrids, vinyls, nylon, phenolics, etc.

Oscillator - Device used to move automatic guns in a vertical plane to provide uniform and increased powder coverage. Motion is provided by a wheel and arm mechanical device within the unit. Radial oscillators, or wagglers, move the guns in an arc motion.

OSHA - Occupational Safety and Health Administration; government enforcement agency for safety issues in U.S. industry.

Overall Efficiency - The product of the compression efficiency and the mechanical efficiency.

Overatomized - Powder that has been dispersed too finely but by use of excessive atomizing air pressure.

Overbake - Applying more heat in time and/or temperature than is required for cure. Overbake is the result of curing paint film at too high of a combination of time and temperature. The film often becomes too hard and may embrittle and/or color and gloss may be adversely affected.

Overspray - Material that does not deposit on the part of rack and goes to the recovery system.