Abrasive
Agent used for abrasive blast cleaning, i.e., sand, grit, steel shot, glass beads.    

Absolute Filter
An air purifier or filter capable of collecting particles down to 2-3 microns.    

Absolute Pressure
See "Pressure - Absolute."

Absolute Viscosity
See "Viscosity - Absolute."

Absorption
Process of soaking up or assimilation of one substance by another.

Accelerator
Catalyst. Material which accelerates the hardening, or "cross-linking," of a mixture of polymers or resins.

Accumulator
Vessel for pressurized fluid storage for a source of fluid power to dampen fluctuations.

Acetone
Powerful lacquer solvent of the ketone-type. Formula: CH3-CO-CH3. (Acetone is a fast evaporating, highly flammable solvent.)

Acicular Pigments
Pigments whose particles are needle-shaped.

Acoustic Paint
Paint which absorbs or deadens sound.

Acrylic Ester
An ester or a derivative of acrylic acid (methyl metacrylate).

Acrylic Resin
A clear resin derived from polymerized esters of acrylic acid and methacrylic acid. (Acrylics are widely used as automotive and appliance topcoats. Physical properties can be controlled in part by choice of alcohol to make the ester.)

Activator Catalyst or curing agent. Accelerator.

Active Solvent A liquid which can dissolve a resin when used alone.

Additives Any one of a number of special chemicals added to a paint to bring about special effects. (Examples: plasticizers, light stabilizers, fungicides.)

Add-on Control Device Equipment (such as incinerators) added to a system to control air pollution in an exhaust gas. (Add-on's do not affect the controlled process. EPA regulations apply.)

Adhesion Bonding strength. Attraction of coating to the surface to which it is applied. Property that causes one material to stick to another. (Adhesion is affected by the condition of the surface to be coated, by closeness of contact, as well as by molecular forces of unlike substances. The surface being coated should allow a certain amount of penetration, be chemically clean, not too smooth, and be hard, or non-porous, to achieve good adhesion.)

Absorption Process of attraction to a surface.

Attachment. Retention of foreign molecules on the surface of a substance.

Adulteration The addition of unwanted materials.

Aerosol Dispersion of a liquid or solid into a gas.

Affected Facility "Referring to a stationary source: any apparatus to which a standard is applicable." - source, E.P.A. Agglomerate To gather into a ball, mass, or cluster. (In paint - agglomerates tend to settle out and have poor optical properties. In powder - agglomerates have poor dispersion in transport air resulting in formation of lumps on the surface of powder which will not flow out when cured.)

Aging A finishing material is said to "age" when it is allowed to stand for some time to improve flowing, brushing, or other qualities. (Label varnish is allowed to stand, or age, until the finally-divided particles present have separated and settled to the bottom of the tank. Aging of such materials will vary and depend on the type of materials used, and the properties sought after.)

Air Adjusting Valve Spray gun valve controlling input air.

Air Atomizing Hot Spray See "Hot Spray - Air Atomizing."

Air Breather Device permitting air movement between atmosphere and the component in which it is installed. (An example of air breathers is an air filter.)

Air Bubble Bubble in paint film caused by entrapped air.

Air Cap/Nozzle Perforated housing (at the head of a spray gun or nozzle) which directs compressed air against paint to form and shape it into an atomized cloud of droplets.

Air Classifier Device used in powder coating manufacturing to classify particle size. (Removal of fines is accomplished by air suspension and vacuum removal).

Air - Compressed Air at any pressure greater than atmospheric pressure.

Air Dry Coating dried or cured at ambient temperature.

Air Drying Drying (polymerization) by oxidation, or by evaporation of solvents, due to exposure to air. (A finishing material is said to be an air drying material when it is capable of hardening, or curing, at ordinary room temperature, i.e., 60-80°F.)

Air Entrapment Inclusion of air bubbles in paint film.

Air Flow See "Air Velocity."

Air - Free Air under pressure due to atmospheric conditions at any specific location.

Air Hose See "Hose." (An air hose should be oil- and water-free.)

Air Spray Paint application system wherein paint is atomized by combination with compressed air.

Airless Spray System of applying paint, where paint under high pressure is passed through a nozzle and broken down into droplets, or "atomized," when it enters the lower pressure region outside the gun tip. (Less air is used than in conventional air spraying so that the problems of dry spray and paint bounce-back are reduced.)

Airless Spray Cap Perforated housing for atomizing paint (without the use of air) at the head of a spray gun.

Air Lock Device for metering powder into a sieve.

Air Manifold Common air supply chamber for several lines.

Air Spray System of applying paint in the form of tiny droplets in air, i.e., paint is broken down into droplets, or "atomized," by a spray gun as a result of being forced into a high velocity air stream. Shape and paint density of the resulting droplet cloud can be controlled by air pressure, paint viscosity, and gun tip geometry.

Air - Standard See "Standard Air."

Air-to-cloth Ratio A ratio comparing the total number of filter media in square feet to the air volume capacity of the filter in ft.3 per minute.

Air Transformer Device for controlled reduction in air pressure.

Air Valve Control valve in an air line system.

Air Velocity Measured air speed - typically measured in feet per minute.

Air Volume Quantity of air in cubic feet.

Alcohol Flammable solvent. (Alcohols commonly used in painting are: ethyl alcohol "ethanol;" and methyl alcohol "methanol," or "wood alcohol.")

Aliphatic Hydro Carbons Type of solvent comprised mainly of straight chain hydrocarbons - usually petroleum derivatives. (Examples: gasoline, kerosene, Hexane, and Naphtha.)

Alkali Caustic. Capable of dissolution by chemical action. (Example: sodium hydroxide or caustic soda, lye, etc.)

Alkyd Resin Resins prepared from polyhydric alcohols and polybasic acids. (Alkyd resins are widely used in general industrial enamels, automotive primers, and water-based house paint. They may be solvent- or water-based.)

Alligatoring Surface imperfections of paint having the appearance of alligator hide.

Alternative Method "Method of sampling and analyzing for an air pollutant that is not a reference or equivalent method but has been demonstrated to the Administrator's satisfaction to, in specific cases, produce results adequate for his determination of compliance." - source, E.P.A.

Ambient Temperature Room temperature or temperature of surrounding area.

Amides Organic compound - used as a curing agent when combined with epoxy resin. Contains the CONH2 group.

Amines Any of a group of organic compounds of nitrogen - used as a curing agent when combined with epoxy resin - contains the NH2 group.

Amorphous Absence of crystallinity in a binder resin. (Most paint binders are amorphous.)

Anchor Pattern Profile of a surface - usually attained by blasting.

Angle of Degree Orifice angle. Pattern angle - "Airless Spray Cap." (Controls width or spray.)

Angstrom Unit Unit of equal length to one hundreth-million (108) of a centimeter. (Used to specify radiation wavelengths.)

Anhydrous Dry - free of water in any form.

Anodic Electrodeposition See "Electrodeposition." (Target substrate is anode or positive; paint is cathode or negative.)

Anti-foaming Agent Ingredient added to materials in chemical processing to reduce their tendency to foam. (Anti-foaming agents - such as common Octyl alcohol - are especially important to water-thinned paints, both in manufacture and applications.)

Antioxidant Oxidant inhibitor. An additive (usually incorporated in a relatively small proportion) which prevents or reduces chemical oxidation or weathering.

Anti-skinning Agent Chemical(s) added to a varnish or an oil to prevent formation of a surface film of partially oxidized material, or "skin," on the surface of a liquid while in a container or before being applied to workpiece.

Antique Finish Finish designed to give the appearance of age to the article being finished. (An antique finish is usually achieved by high lighting parts normally receiving the greatest wear or by darkening unworn portions to simulate the accumulation of smoke and dirt.)

Apparent Viscosity The ratio of shear stress to rate of shear of a non-Newtonian fluid, calculated from Poiseuille's equation and measured in "poises." (The apparent viscosity of most greases vary with the changing rates of shear and temperature - therefore they must be reported as the value at a given shear rate and temperature.)

Application Process of applying a coating to a substrate or previous coating of material. Principal methods of applying finishing materials are: brushing, spraying, dipping, roller coating, flowing, tumbling, squeezing, stenciling, and printing. (When the entire surface to be coated has been covered - an application has been made. When the same surface is recoated - a second application has been made. Two or more applications may be considered as one coat if the normal drying time was not allowed between applications.) Applicator Tool for applying or one who applies coating material. Applied Solids Solids remaining on a substrate to which paint or powder has been applied. Architectural Coatings Those coatings specifically manufactured to withstand environmental weathering. Off-the-shelf coatings, i.e., available through retail purchase. Ref. "Trade Paints." Arcing Act of swinging spray gun away from the work. Or… (2) electrical discharge from gun electrode to the part being coated. (Arching is generally caused by poor ground.) Aromatic Solvents Hydrocarbons. Type of solvent derived from benezene-ring molecules. Hydrocarbons derived from, or characterized by, the presence of unsaturated resonate ring structures. (Aromatics are often used as diluents. Example: Benzene, Toluene, Xylene.) Asphalt Residue from petroleum refining - also a natural complex hydrocarbon. Atmospheric Pressure See "Pressure - Atmospheric." Atom The smallest unit of an element. Atomic Absorption Analytical instrument used to detect and quantify metal ions from aqueous solutions by injecting dilute solutions of unknown chemical compounds into a flame of known heat intensity and optical transparency; measuring absorption by optical and differential thermoelectronics circuitry. Atomization Paint Spraying - the formation of tiny droplets of liquid. Powder Coating - the separation of powder particles into air. Atomizing Air Air injected into liquid or powder path to atomize them into a mist or cloud. Attriter Mechanical dispersing device utilizing steel balls in cylindrical container. (Liquid paint is pumped in bottom and flows out exit port at top - pigment is dispersed by revolving metal balls in centrifugal fashion.)   Automatic Feedback Current Control (AFC)An effective, field-proven method of delaying back ionization, improving recess penetration and finish smoothness with Nordson electrostatic corona-charging powder spray systems. In traditional electrostatic powder spray systems, gun current widely fluctuates with changes in distance between the gun and part. Thus, operating current level often exceeds an optimum level that results in an excessive number of free ions that build up on the coating layer. This produces back ionization that reduces operating transfer efficiency and leads to the formation of pinholes on the surface of the powder-coated part. With AFC control, free-ion current produced by the spray gun is tightly controlled and not to exceed an operator-preset optimum level for a given application. Such precise control of gun current delivers maximum powder charging without an excessive number of free ions which delays back ionization. More information on Nordson AFC control can be found in the technical paper "Electrostatic Phenomena" in the Library.   ©1990 Society of Manufacturing Engineers©1999 Nordson CorporationAll rights reserved   Site Map | Technology | Equipment | Customer Service | Technical Forum News & Events  | Library  |  Contact Us   Powder Coating Systems  |  Nordson Corporation