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Coating Terminology

  • Abrasion
    A wearing, grinding, or rubbing away by friction.
  • Additive
    A substance added to a formulation in relatively small amounts to impart or improve desirable properties or suppress undesirable properties.
  • Adhesion
    A coating's ability to adhere to the substrate.
  • Alkaline Wash
    Cleaning process that employs a high pH solution (caustic). A good choice for parts with little buildup of contaminants.
  • Alternative Energy
    The term Alternative Energy has many meanings in today’s environment. The most common: A form of creating energy that does not cause carbon dioxide emissions. For example, Fuel cells, Wind Generators, and Hydrogen Cells are the most talked about. Alternative energy coatings are used to stop corrosion caused by chemical reactions.
  • Aluminum Oxide
    Hard particulate medium used in grit blasting to clean and roughen surfaces that are to be coated.
  • Annealing (metallurgy)
    A heat treatment that alters the microstructure of a material causing changes in properties such as strength and hardness.
  • Anodizing
    Creating a hard oxide surface on aluminum parts via an electrolytic process. Unsealed anodized surfaces have a porosity that makes them excellent substrates for coatings. This is not an application method that Decc currently performs.
  • ASTM
    American Society of Testing Materials
  • Binder
    Tough polymer that acts as an adhesive to join elements of matrix coatings.
  • Burn off
    A method of removing a coating. Temperature is elevated above the degradation point of the coating and held there until the coating breaks down. Also a method used to clean a metal surface. (See surface preparation).
  • Burnishing
    Process of polishing cured coating to improve release and low friction.
  • Carrier
    The liquid portion of a coating (solvent or water) in which solids are dissolved or suspended.
  • Coefficient of Friction (COF)
    A number expressing the amount of frictional effect usually expressed two ways: static or dynamic.
  • Conductor
    Material that can support flow of electrical current. Fluoropolymer coatings are normally insulators, but can be modified with certain fillers and pigments to make them conductive.
  • Corrosion
    Process of metal decomposition (oxidation) in which metal ions are united with oxygen to form metal oxides. Fluoropolymer coatings provide excellent barriers against most corrosives.
  • Cross Linking
    Quality of thermosetting plastic resins in which polymer chains combine during curing process. In general, the greater the cross linking, the tougher and more chemically resistant the coating.
  • Cure Time/Temp
    The time/temperature relationship that the part must see which is required to cure that specific coating so it can develop its specified properties.
  • Curing
    Process of bonding or fusing a coating to a substrate with heat and developing specified properties in the coating.
  • Die Casting
    Alloy casting process commonly used to produce high volumes of intricate parts. The process sometimes entraps small bubbles in the metal that can result in "blow holes" when the coating is cured.
  • Dielectric Strength
    Ability of a coating to resist the passage of electric current.
  • Dip/spin
    Coating application technique in which small parts are placed in a basket that is lowered into a coating bath, then raised and spun to remove excess coating. An economical system for coating high volumes of small parts. This is not an application method that Decc currently performs. For Decc’s alternative economical system for coating high volumes of small parts. (See Tumble Coat).
  • Dry (solid) Lubricants
    Solid materials such as PTFE, PFA, FEP, ETFE, Moly Disulfide (MoS2) and graphite that have low coefficients of friction.
  • Elastomers
    Any of various elastic substances resembling rubber.
  • Electrostatic
    A deposition method of charging fluidized coating so that it is deposited onto a substrate (usually grounded).
  • Electrostatic Spray
    A deposition method of spraying and charging a coating so that it is deposited on a substrate (usually grounded). A spray application process in which the coating and part to be coated are oppositely charged (referred to as electrostatic coating); process provides excellent "wrap" of coating around the part, even on sides opposite the spray gun. (See Faraday Cage Effect).
  • Engineering Plastics
    Plastic resins that have high-performance properties such as high temperature stability, hot hardness, abrasion resistance and corrosion resistance.
  • Environmental Regulations
    Federal, state or local laws, statutes or regulations of which their intent is to protect human health and the environment. Examples are the Clean Air Act (CAA), and the regulations which govern the storage, transportation and disposal of hazardous waste, the Resource Conservation and Recovery Act (RCRA).
  • Epoxy
    A flexible resin, usually thermosetting, made by polymerization of an epoxide and used chiefly in coatings and adhesives.
  • ETFE (Ethylene Tetrafluoroethylene)
    Is a copolymer of Ethylene and Tetrafluoroethylene. ETFE is a thermoplastic member of the Fluoropolymer family. ETFE is noted for exceptional chemical resistance, toughness and abrasion resistance. Although not fully fluorinated, ETFE has excellent chemical resistance and can operate continuously at 150° C/300° F. This resin is the toughest of the Fluoropolymers and can be applied at film builds up to 1,000 micrometers (40 mils) to provide a highly durable finish.
  • Faraday Cage Effect
    Repulsion of charged particles because of the part's concave shape. Charges build at the entry area, preventing penetration into the cavity.
  • FEP (Fluorinated Ethylene Propylene)
    A thermoplastic member of the Fluoropolymer family. FEP has excellent non stick and non wetting properties, in addition to low friction. These coatings provide excellent chemical resistance. Maximum use temperature is 205° C/400° F.
  • Fillers
    Pigments and other solids used to alter properties of coatings.
  • Film Formation
    A continuous film formed due to heated polymer particles melting and coalescing or cross-linking.
  • Flash Point
    The lowest temperature at which a solvent will generate sufficient vapors to ignite in the presence of flame.
  • Flashing
    A brief sub cure (at lower temperatures than the final cure) to drive off solvents or carriers prior to full cure. This helps prevent bubbling. (See Partial Cure).
  • Fluoropolymers
    Family of engineering plastics containing fluorine, characterized by high thermal stability, almost universal chemical resistance and low friction.
  • Friction (Dynamic)
    Resistance to continued motion between two surfaces; also known as sliding friction.
  • Friction (Static)
    Resistance to initial motion between two surfaces.
  • Graphite
    A carbon-based dry lubricant that is preferred for high-temperature applications.
  • Grounding
    Being electrically connected to earth or a negative charge.
  • Hydrogen Embrittlement
    Embrittlement of carbon steel caused by absorption of atomic hydrogen in plating, pickling or acid cleaning processes.
  • Intercoat Adhesion
    A coating's ability to adhere to previously applied films, including primers.
  • Melt Point
    The temperature at which a polymer particle will begin to melt and flow.
  • Micron
    Is commonly used in the coating industry, is equivalent to 1/25th of a mil, i.e., 25 microns are equivalent to one mil of coating thickness, or one mil of coating thickness is equivalent to 25 microns.
  • Mil
    One thousandth (0.001) of an inch (25.4 microns). This is the most common non-metric measurement of coating thickness. (This is the measurement system that is used at Decc).
  • Moly, Moly Disulfide, Molybdenum Disulfide, MOS2
    Four names for the same naturally occurring substance that has good low-friction and high load-bearing properties.
  • Noise Damping/Reduction
    The absorption of sound vibrations. Fluoropolymer coatings form good noise damping surfaces.
  • NVH (Noise, Vibration, and Harshness)
    The term generally used to describe unwanted vibrations in a automobile. NVH is a generic term/acronym that covers the branch of engineering relating to vehicle refinement in terms of noise (acoustic) and vibration experienced by the occupants when the vehicle is in service. The term is used mainly in connection with road vehicles, but exactly the same techniques are used in air and rail transport to improve refinement.
  • Partial Cure
    Process sometimes utilized when multiple layers of Fluoropolymer coatings are to be applied. The first coat is incompletely cured. The second coat is applied and both are fully cured together. (See Flashing).
  • Pencil Hardness
    A value determined by measuring the relative hardness of a coating based upon the ability of the coating to resist penetration and gouging by pencil lead of varying hardness. The order of pencils from softest to hardest is 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, and 8H. The hardness rating of the coating is equal to the first pencil which does not penetrate and gouge the coating.
  • PFA (Perfluoroalkoxy)
    Thermoplastic member of Fluoropolymer family of engineering plastics. The additional benefits of higher continuous use temperature (260° C/500° F), film thicknesses up to 1,000 micrometers (40 mils) and greater toughness than PTFE or FEP. This combination of properties makes PFA an excellent choice for a wide variety of uses especially those involving chemical resistance. PFA is characterized by excellent release, low friction and toughness.
  • Phenolic
    A resin or plastic, usually thermosetting, made by condensation of a phenol with an aldehyde and used for molding, insulating, coatings and adhesives.
  • Phosphating
    Surface pretreatment used on ferrous or aluminum parts that provides a very thin crystalline film that enhances both corrosion resistance and adhesion. (A microcrystalline zinc phosphate process “250 milligrams +/- 50 per square inch” is used at Decc).
  • Pigment
    Finely divided, insoluble colored substance used to impart color to a coating.
  • Polyurea®
    Is an elastomer created by the chemical reaction between an isocyanate and an amine. Attributes include abrasion protection, corrosion protection, chemical resistance, noise reduction, slip/grip, and additional strength qualities (to some substrates).
  • Postcure
    A second cure at high temperature to enhance specific properties such as release and non-wetting.
  • Postforming
    Process of shaping parts after a coating has been applied and cured, a technique commonly used with stamped, blanked or spun parts.
  • Powder Coatings
    Finely divided particles of organic polymers, pigments and additives. (Powder coating is not a common process at Decc, except in the case of unique masking requirements, or requirements for Ryton Powder).
  • Powder Metal
    Material formed by compressing particles and heating (sintering) to solidify and strengthen them.
  • Preheating
    Warming of parts prior to application of a coating, recommended when adhesion is critical and when parts are being coated in humid atmospheres. In some cases, this technique can be used to achieve higher-than-normal film builds.
  • Pressure Spraying
    Coating technique similar to siphon spraying, except that the coating is delivered from a pressurized pot to the spray nozzle under positive pressure. Generally used for high-volume production.
  • Pretreatment
    Processes for cleaning and conditioning a substrate to be coated. Next to the choice of coating, this may be the most important factor in the use of high-performance coatings.
  • PTFE (Polytetrafluoroethylene)
    A thermoplastic member of the Fluoropolymer family of plastics. It is a two-coat system (primer/topcoat). PTFE has an extremely low coefficient of friction, good abrasion resistance, good chemical resistance, and the highest operating temperatures of the Fluoropolymers (290° C/550° F).
  • PVDF (Polyvinylidene Fluoride)
    High-molecular weight thermoplastic of vinylidene fluoride with excellent strength, wear resistance and creep resistance.
  • Resistance (electrical)
    The opposition offered by a coating to the passage of an electric current through it.
  • Salt Fog
    ASTM B-117 test procedure that simulates the corrosive environment caused by road salt and marine spray.
  • Sand Blasting (also grit blasting)
    The process of surface cleaning and roughening that provides a mechanical "tooth" to aid coating adhesion. Media include aluminum oxide, even crushed walnut shells. The medium must be chosen to match the substrate and the foreign material on the substrate to be removed. (We utilize the aluminum oxide media here at Decc) (See Aluminum oxide).
  • Sintering
    A process where the temperature of PTFE is raised to the point where PTFE particles soften and form a bond with each other.
  • Siphon Spraying
    Most common technique for applying coatings, also known as "conventional air spray." The coating is drawn from a reservoir into an atomizing air nozzle and propelled toward the surface to be coated.
  • Stick-up
    This is the build-up of coating on a part. Often a concern on a mechanical fit. To compensate for coating stack-up, parts often have to be machined down to allow for the coating build-up.
  • Storage Stability (Shelf life)
    The ability of a coating material to maintain uniform physical and chemical properties while in storage over an extended periods of time. Most coatings have a shelf life, some even have a shelf life after they have been applied – as in the case of rubber to metal adhesives.
  • Substrate
    Any surface to be coated. This can include metals such as steel, cast iron, bronze, brass, aluminum, stainless steel, chromium and, with special precautions, nickel. Paper, most plastics, wood, leather, fabrics and glass can also be coated.
  • Surface Appearance
    The smoothness gloss and presence or lack of surface defects in a coating.
  • Surface Preparation (Burn off)
    The removal of a coating by elevating the temperature of the part(s) above the degradation point of the coating and holding it until the coating carbonizes (See Burn Off).
  • Surface Treatment
    Conditioning the substrate before coating through grit blast, phosphate, etc. May include the removal of a coating (See Burn Off).
  • Teflon®
    "TEFLON® is a registered tradmark of DuPont." For more information, see Merriam-Webster online dictionary (www.m-w.com/dictionary), Concise Encyclopedia: Teflon: Trademark for a polymer of tetrafluoroethylene fluorocarbon (polytetrafluoroethylene [PTFE]). Function: trademark --used for synthetic fluorine-coating resins used especially for molding articles and for nonstick coatings. Learn more about "Teflon" and related topics at Britannica.com. A closely related fluorocarbon polymer, fluorinated ethylene-propylene (FEP), has properties and applications similar to those of Teflon®. (See PTFE, PFA, FEP, ETFE, Dry lubricants).
  • Tetrafluoroethylene (TFE)
    A monomer used as a chemical feedstock in the production of PTFE.
  • Thermoplastic
    Plastic resin that softens when reheated and hardens when cooled.
  • Thermoplastic Resin
    A resin which will melt when heated and solidifies when cooled, and softens when reheated.
  • Thermosetting Resin (Thermo set)
    A resin designed to undergo an irreversible chemical and physical change when undergoing a heat-cure schedule, i.e., A plastic resin that cross links during cure so that it does not soften when reheated.
  • Transfer Efficiency
    The ratio of the amount of coating deposited on a substrate.
  • Tumble Coat
    A deposition method of spraying coating a group of small parts as they tumble in front of a spray gun. This is an economical method of coating small bulk parts. Due to the nature of this application method some parts will exhibit material build-up, tangling, sticking or scuff-marks.
  • Wear
    Deterioration by friction (abrasion, spalling, cutting, fretting).
  • Wrap
    A characteristic of liquid and powder coatings in electrostatic application to adhere to areas of the substrate not in direct line of sight of the delivery system end point.