Backbone Chain Base chemical utilized to polymerize a chemical compound or resin. (Example: Epichlorohydrin and Bisphenol-A for epoxy resins.) Back Ionization Condition occurring when excessive build-up of charged powder particles limits further powder from being deposited on the substrate. (Back ionization may occur during electrostatic applications and can reverse the electrical charge of the surface layer of powder particles. This condition may also be referred to as "electrostatic rejection" and/or "repelling.") Back Pressure See "Pressure - Back." Baghouse Powder collector system utilizing a bag-type filter media to separate powder from transport air. Baking Process of drying a coating material by application of artificial heat. (Forced drying is a mild form of baking - temperatures of 100°-150°F are used compared to the 175°-400°F necessary for baking. Applications of heat greatly reduces drying time.) Baking Finish Coating requiring heat to cure the film. (A baking enamel, japan, paint, or varnish is one which requires elevated temperatures to become hard and dry). Ball Mill Device for displaying/grinding a pigment into a liquid paint vehicle. (A ball mill is essentially a large ceramic-lined rolling drum to which ceramic balls or stones are added to mechanically disperse and wet the pigments.) Barrier Coating Shielding, or blocking, coating or film. (Example: a coating to protect lacquer solvents from attacking plastic substrates.) Basecoat First coat applied to a substrate. Primer. Underneath coat. Basecoat/Clearcoat Application system in which a highly-pigmented underneath coat is followed by clear-coat which acts as a protectant for the basecoat. (Often used in automotive finishing.) Baume´ Scale Specific gravity scale used for taking the relative weight of a liquid as compared to the weight of an equal volume of a standard liquid. (The "lighter-than-water" or "oil" scale has, at its zero point, the distance to which a hydrometer sinks in a mixture of one part of salt in nine parts of water. The 10° point is determined in pure water. The distance between these two points is then divided into ten equal parts and these same spaces are added above the 10° mark as high as may be required for the liquid in which the hydrometer is most frequently used. The "heavier-than-water" or "acid" scale uses pure water for its zero point. The point to which the hydrometer sinks in a mixture of 15 parts of salt to 85 parts of water is market 15°. Between these two points, the space is divided into 15 equal parts and these same size spacings are added below the 15° mark to make a total scale of 0-70°.) - Antoine Baume´ Bell Electrostatic spray device whose paint applicator is bell-shaped. (The bell's revolution is so rapid, it centrifugally throws paint off its edge into a fine mist. The charged particles are then attracted to the target substrate. At 90% transfer efficiency - the bell is one of the most cost-effective applicators.) Bernouli's Law "If no work is done on or by a flowing, frictionless liquid, its energy due to pressure and velocity remains constant at all points along the streamline." - Daniel Bernouli Beta Rays Beams of electrons which can be used to cure certain kinds of paint. Binder Film former vehicle - so called because it binds pigment and any additives present into a solid durable film. The nonvolatile liquid portion of a film. (Usually resins, drying oils, latex emulsions, etc.) Bite When a top coat material partially dissolves or softens an underneath coat, it is said to "bite" into the undercoat. Bituminous Coating Coal tar- or asphalt-based coatings. Blast Angle Angle of nozzle with reference to a surface. (Also angle or particle propelled from rotating blast cleaning wheel with reference to a surface.) Blast Cleaning Cleaning with air- or jet-propelled abrasive. Bleaching Removing color by means of chemical treatment and/or ultraviolet light. Bleaching Agent Material (when properly used) that permanently lightens the color of the object on which it is used. (Example: Sodium Hypochlorite or oxalic acid solutions.) Bleeding Defect in which pigment from a previous coat of paint diffuses into a topcoat resulting in the discoloration of the topcoat. Bleeder Gun Spray gun with no air valve - the trigger controls fluid flow only. Blistering Formation of bubbles or water droplets in a paint film. (Blistering is usually caused by the expansion of air, solvent vapor, or moisture trapped beneath the film. Blisters can form around chemical or pretreatment salt crystals trapped under a paint film because the salts attract moisture and dissolves. They can also be caused by exposure to excessive heat; by grease or other volatile materials under the finish; by moisture in wood; or by too frequent application of coating material. Anything which causes a gas or vapor to form under the film, may cause blistering.) Blooming Whitening. Clouding. Powder-like deposit which sometimes forms on the surface of a paint film. (Blooming is often the result of a solvent component partially dissolving the pigment(s) and depositing them on the surface film during solvent evaporation.) Blow-back Rebound of atomized or sprayed paint/powder particles. Blowing Agent See "Foaming Agent." Blushing The appearance of whitish areas in a paint film during the drying period. Condition is caused by the partial (or total) precipitation of the solid ingredients as a result of condensed moisture in the film (because of excessive humidity or improper solvent balance); the true solvents evaporate first and the diluent, or nonsolvent portion, evaporate later - blush retarder usually corrects this problem. (Blushing often occurs when rapid evaporation of solvent cools the air over the painted surface below dew point.) Body Viscosity - used to describe the fullness or thickness of a liquid, or that of a film of coating on a workpiece. Or… (2) middle or undercoat. Bodying Agent Material added to a protective coating to increase viscosity. (To "thicken" or to give "body.") Boilers Solvents of particular evaporation rate, i.e., "low boilers" and "high boilers." Bond Coat Coating used to improve the adherence of succeeding coats. Bonding Adhesion or secure joining of paint-to-paint or paint-to-substrate. Bounce-back Spray rebound similar to "blow-back." Boxing Mixing by pouring back and forth from one container to another. Boyle's Law "The absolute pressure of a fixed mass of gas varies inversely with the volume provided the temperature remains constant." - Robert Boyle Branched Polymer Polymer with some branching along its backbone chain. (Example: low density polyethylene.) Bridging Ability of a finishing material to cover cracks, voids, or small gaps without breaks in the film - usually resulting in an air pocket under the dried film. (Bridging is usually a defect to be avoided, but is sometimes desirable in certain special finishes.) Bright Blast White metal surface blast. Brittleness Degree of resistance to cracking, breaking, or bending. Broadcast To sprinkle solid particles on a surface. Bronze Tools Non-sparking tools. (Bronze tools are used when fire hazards are likely.) Bronzing Formation of a metallic sheen on paint films which is caused by pigment "flotation" or "flocculation." Brushability Ease of brush application. Brush-off Blast Lowest blast cleaning standard. Bubbling Term used to describe the appearance of blisters. (Bubbling is the result of any condition that causes air, vapors, or gases to be trapped within a film while it is soft - but still sufficiently hard to prevent the escape of gas.) Building Coat Finishing material (usually of a transparent nature) used over the sealer or color coats and under the finishing coats to increase the fullness of the finished work. Bulk Blender Device used in powder manufacture to mix multiple batches of powder resulting in a homogenous blend. Bulk Density Solid mass per unit of volume. Bulk Modulus Measure of resistance to compressibility of a fluid - reciprocal of the compressibility.