Glossary
Abrasion Resistance - Ability to withstand removal of the coating surface by repeated physical abrading.
Additives - Trace amounts of liquids and/or solids that are added to paint for the purpose(s) of application ease and to achieve specified characteristics.
Adhesion - The level of bonding that has been created between the metal substrate, the pretreatment and the paint coating.
Accumulator - A series of fixed and movable rolls, which act as a reservoir of strip in a continuous coating line. Typically, accumulators are located at both the beginning and the end of a coating line. The purpose of an accumulator is to provide enough excess strips to avoid the necessity of stopping a continuous processing line when a new coil is attached at either the entry section or when a finished coil is removed from the exit section of the line.
Alkyd - An oily, fatty-based resin with characteristics similar to polyester. An Alkyd can be readily substituted with a polyester system.
Applicator Roll - The roll (in a coating machine) that is used to apply the paint, conversion coating or other liquid to a moving metal strip. An applicator roll can be run in reverse or trailing the strip direction.
Backer - A two coat system that is applied to the bottom side of the metal strip. The backer is generally specified with reference to its color, gloss and dry film thickness. The backer is a two-coat system with a typical dry film thickness (total including primer) of 0.40-0.50 mils. The function of the backer may be for appearance, durability or lubricity during roll forming and corrosion protection during installation/use. A backer coating is a normal component for a building product application.
Baffle - A device used for deflecting material (i.e. paint) in a desired direction. The following are examples of a baffle: A piece of metal placed in a roll coating pan that directs the flow of paint to the pick-up roll. A piece of metal extending under the surface of the paint (in the coating pan) to direct air bubbles away from the pickup roll.
A piece of metal used in an oven to direct the flow of air in a desired direction.Blocking – A defective condition where one layer (or wrap) of a painted coil sticks to an adjacent layer or wrap.
Body – A term describing the consistency (or viscosity) of a paint.
Bonderizing - A generic term that has evolved based on the Henkel Corp.; trade name for chemicals called Bonderites. Bonderizing does not indicate any particular type of pretreatment. When this term is used, the pretreatment must be specified.
Bridle Roll(s) - A series of rolls that provide tension and/or driving force to the metal strip as it moves through a continuous coating line.
Clear Coat – A coating that does not have pigmentation. It is used to achieve gloss development or to protect the pigment coating under it.
Camber - Camber is the deviation of straightness of a strip edge from a straight line. The measurement of the level of camber is taken on the concave side, using a straight edge. Long lengths of unsupported strip having a large amount of camber can deviate from the horizontal or slope to one side.
Center Stretch (Full Center) - A phenomenon whereby the center of the strip is longer than the edges, so that the strip is not flat. See Oil Can.
Chatter - Transverse perpendicular rows of varying film thickness on the painted strip. The marks are usually due to vibration of the coating rolls, strip or to an eccentric roller.
Chemical Treatment - A process where the surface of bare steel is passivated by applying an acidic solution that etches the surface. The purpose is to render the surface inert to oxidation.
Chromate Conversion – A process where aluminum or aluminized steel substrate surface is converted to a non-metallic, nonconductive, inert, amorphous complex chrome oxide coating. This is considered a conversion coating. The major components are chromic acid, nitric acid and hydrofluoric acid.
Chrome Free - A process for treating of aluminum alloys and metal for environmental or food contact concerns.
Cleaning Section - The portion of the coil coating process where the strip is prepared for painting. This process includes High Pressure Washers, Mechanical Scotch Brite brushes, Alkaline Spray cleaning and Hot water rinsing. This section is designed to remove “tramp” oils from the strip surface. Air knives are utilized to dry the strip prior to painting.
Clock Spring - The slipping action of one wrap on an adjacent wrap that can occur in a coil when the strip is being recoiled or uncoiled.
Coating - A layer of some paint material covering the strip surface.
Coating Weight - The amount of conversation coating or other material deposited by a metal treating compound. It is measured in weight per surface area, such as milligrams per square foot of surface area. Can coating weights are also measured in a similar manner, such as milligrams per square inch.
Coater or Roll Coater - An apparatus that applies paint, conversion coating(s) or other liquids to a metal strip surface. The coater apparatus consists of rolls, which support the strip through the apparatus while at the same time are able to pick up, meter and deposit the coating material onto the moving strip.
Cold Rolled Steel – A metal substrate consisting of plain carbon steel that is typically soft (annealed) and does not have any metallic coating.
Color - This is a visual and numeric comparative to a prescribed, precise shade. It is typically referred to as a color standard. A complete color definition includes a coated metal panel that depicts all of the deviations from the prescribed color.
Complex Oxides - A cobalt accelerated, alkaline/iron oxide that converts the metal substrate surface to a non-metallic, non-conductive inert amorphous oxide coating. This is considered a conversion coating. The major components are sodium hydroxide, soluble metallic cobalt and soluble metallic iron.
Concentric Roll - A perfectly round roll. A roll with all locations on the circumference being equidistant from the axis of the roll (when it revolves).
Conversion Coating - A chemical treatment normally applied to the metal strip prior to final finishing. It is designed to react with the metal and modify it to obtain a suitable surface for painting or adhesive bonding.
Cratering - A coating defect related to surface tension. It is characterized by small pockmarks or indentures surrounded by a ring of coating material projected above the general plane of the coating. In severe instances, the area in the center of the crater may show the substrate. Craters are typically caused by contamination of the surface.
Diluents - A liquid that makes a solution thinner by adding volume to cause dispersion.
Direct Coating - A method for applying a film of material with a coating roll that revolves in the same direction as the travel of the strip. This is also referred to as forward coating.
Drawability - The amount of elasticity to allow for stretching of the metal and/or coating.
Dry-In-Place – An environmentally efficient process where a surface treatment chemical can be applied uniformly over aluminum, steel, aluminized steel, galvanized steel and galvalume. This is not considered a conversion coating.
Durometer Hardness Tester - An instrument for the determination of hardness of elastomers or other compressible rubber-like materials, commonly used for hardness measurement of roll coverings and heavy film of plastic (e.g. plastisols) . Test results are displayed as a percentage of scale deflection from 0 to 100 for any given scale employed. (Most commonly used: scale “A”).
Electro-Galvanized Steel – A cold rolled steel substrate that has a thin coating of pure zinc that is electrolytically deposited to the surface.
Enamels – Specific coatings that are baked on to achieve a glossy, hard, decorative finish.
Entry Section - This refers to the area where material is loaded on to the paint line. It typically consists of two payoff arbors, which uncoil the strip. The entry section includes a shear for squaring the lead edge of the strip or to remove minimal damage of the coil O.D. and mechanical stitcher which links coils together for continuous processing.
Entry Tower – A section of the paint line which is designed to allow the strip to feed into the coil line on a continuous basis while the entry section payoff arbors are halted to connect two coils. The line speed is controlled against fluctuations while the tower refills.
Epoxy – Epoxy coatings function mainly as primers to enhance corrosion resistance. Epoxy coatings offer good solvent resistance when used as a primary resign.
Exit Tower - This functions in reverse of the Entry Tower. The Exit Tower will take up the strip as the Exit Section is stopped to remove a processed coil from the coating line.
Exit Section - This segment of the process includes a rewind arbor to recoil the finished, coated metal product. Customer coil size is furnished at this section. The mechanical stitch that connects processed coils is removed at the exit section. Protective films, lubricating oils and wax are typically applied at the exit section. Visual inspection of the finished strip occurs at the exit section of the line.
Exude (Exudate) - The migration of a component or substance in a coating toward the surface during curing or storage.
Extenders - Inert substance used by the paint formulator to aid in increasing volume solids of the liquid coating or to achieve dry film formation.
Fast Solvent - A solvent that evaporates quickly when the coating is cured.
Finish Coater - (See Coater.) The second coater in line where the topcoat is typically applied over a cured primer.
Flexibility - The degree to which a coating can withstand deformation without significant change in the coated surface integrity for cracking, crazing, color and gloss.
Fluoropolymers - This is a premium finish based on the Kynar 500 resin licensed by Elf Ato-Chem North America, Inc. The resin contains 70 percent Polyvinylidene Fluoride.
Finish Coat - A uniform, opaque application of a single coat paint system. The dry film thickness to be applied (in mils) is typically specified on the product data sheet.
Full coat - (See Finish Coat.)
Fish Eye - An elongated crater.
Floating - A process of flooding in which the final color is not uniform and homogeneous.
Flooding – The separation of one or more pigments in a coating during curing so that a non-uniform color or an unintended color is produced.
Flop - The condition where two painted panels appear to match in color when view at one angle and not to match in color at all other angles or where one panel changes color as the viewing angle changes.
Flow - The property of a paint that manifests itself in the degree of leveling or in an ability to flow or move under applied stress.
Four Coat System - Application of any four-coat combination (i.e. primer, base coat , ink, for registered printing, followed by a clear).
Galvalume Steel – A metal substrate consisting of cold rolled steel coated with a metallic coating of 55 percent aluminum and 43.5 percent zinc. Galvalume is a proprietary product that is also marketed as Zincalume.
Galvanized Steel – A metal substrate consisting of cold rolled steel coated with a metallic coating of pure zinc.
Gloss - The luster shininess or reflecting ability of a surface.
Gloss Meter - An instrument for measuring floss usually at 60 or 20 degrees from the vertical.
Half Coat - The coating is to be applied to the bottom side at one-half that of the dry film thickness of the top side. This is typically for single coat systems. A half coat offers better cosmetic appearance than a wash coat.
Hardness Pencil - A method to determine the hardness of paint film. Each of a series of drawing pencils calibrated for hardness is sanded to a blunt point and then held at a 45-degree angle and pushed forward and downward against the panel to be tested. The hardness designation of the pencil, which just fails to cut the film, is the pencil hardness of the film.
Intermediate Coat - Additional coating layer that can contribute to film thickness, bridge incompatible primer-topcoat combinations or provide enhance performance characteristics of the coating system. This is typically an exterior application for coil coating systems and is not commonly found, but this coating is common in post-paint applications.
Iron Phosphate - This chicly converts the steel (iron) surface to a non-metallic, nonconductive, inert, amorphous layer that prevents reaction between the organic coating and the metal substrate. This is considered a conversion coating. The major components are phosphoric acid and nitric acid.
Lacquer - Typically refers to a glossy, hard, clear coating.
Leveler or Roller Levelers - An apparatus containing a series of steel rolls, which flatten or level a metal strip as it passes between the rolls.
Leveling - The phenomenon by which paint flows out to minimize surface irregularities and approaches a smooth surface.
Live Center - A point at the very center of each end of a roll. This is usually a center of the journal in which the roll turns. The roll is driven from these points and considered concentric from the same point.
Mar Resistance - The ability to withstand removal of the coating surface by a mechanical scratching action.
Metal Marking - Black marks left on a painted strip when bare metal is drawn across its surface.
Metamerism - A color state in which two or more painted panels match in color under one type of light but do not match under a different type of light. This usually occurs when different pigment combinations are used to produce the same color.
Meter Roll - A roll used to apply a uniform coating of paint conversion coating or other liquids to transfer roll or an applicator roll.
Micrometer - An instrument used for mechanically measuring the dry film thickness of paints or the thickness of a metal strip.
Migration - The transfer of an ingredient of a paint film from within the film to another part of the film, the surface of the film or to another film in contact with the film containing the migrating substance.
Mil - A unit of measuring thickness: 0.001 inch. Generally applied to paint films.
Oil Can - A localized out-of-flat condition often seen as buckles toward the center of an otherwise flat strip.
Organisol - Higher solids vinyl.
Organic Coating - A liquid, which, when applied, dries and/or cures into thin, solid, functional film. Applications are commonly intended for industrial use. May be clear or pigmented.
Passivation - A surface that is inactive or less reactive to further treatments.
Paint - In the sense of roller coater application, the term paint is used to denote a liquid composition, which is converted to a solid film after application as a thin layer. Usually the liquid will be pigmented.
Pan - An open container at a roller coater which holds the paint, conversion coating or other liquids and within which the pick-up roll revolves.
Peel Coat - A coating applied over a finish coat or topcoat that allows the cured film layer to be removed by physically stripping it off. The function of a peel coat is to protect the finish coat or topcoat from handling damage.
Phosphatizing - The application of a phosphate. The type of phosphate will be specified according to metal substrate.
Pick-Off - Tendency of paint to be picked up in very small pieces from one side of a painted strip and held by the coating on an adjacent wrap of the strip. It also can refer to transfer of coating material to tension and bridle roll.
Pick-Up Roll - A roll revolving within the pan and is partially submerged in the paint conversion coating or other liquids. The pick-up roll picks up paint from the pan and applies it to the transfer or applicator roll.
Pigments - There are two forms of pigments in organic coating, both of which are in a powder form in the virgin state. One form is a coloring substance to achieve a specified color hide. The second is a controlling substance for gloss control. Pigments can be specified as an interior grade or as an exterior grade for corrosion/ultraviolet protection.
Pits - Very small craters.
Plastisol - A thick film coating of polyvinyl chloride that is usually applied at a film thickness ranging from 4.0 mils to 10 mils.
Polishing - An apparent increase in gloss of a paint film caused by the rubbing of the top coat and backing coats during the recoiling of a strip or by contact with roll forming or other smooth moving objects.
Popping - A defect in a paint film usually caused by organic solvents trapped during the curing of the film: fine blistering.
Pre-ship – A sampling of new batch of raw materials (typically paint) that is provided to Quality Control by the paint company for the purposes of evaluating the properties of the paint before it is shipped from the paint company to the coil coater. The sampling may be in the form of a container of liquid paint or metal panel(s) where the paint film has been applied to the surface and cured. Pre-ship analysis may also be referred to as first article testing.
Pressure Marking or Mottling or Streaking - An uneven pattern often seen as glossy spots, which are usually caused by pressures within a painted coil. These become visible during the uncoiling process.
Pre-Primed Coat - An application of a coating intended to be recoated. Dry film thickness is to be specified. The function of a pre-prime is mainly to eliminate the need of pretreatment by the end customer or eliminate production bottleneck in their paint. The method of re-coating by the customer must be fully identified to assure compatibility with the pre-prime coat.
Prime Oven - The Peak Metal Temperature is achieved and maintained momentarily to cure the organic coating. This is a multiple zone oven with individual controls for temperature. The strip hangs in the oven by catenaries.
Primer Coat - Coating applied for its corrosion resistant properties.
Recoiler - The apparatus used to recoil the strip after it is painted.
Resigns - The highly viscous polymer base that establishes the properties of the organic coating. Referred to as the vehicle or bonder.
Reverse coating - Coating with the coating roll revolving in the direction opposite to that of the strip.
Reverse Cure - A fall-off in hardness and solvent resistance of the baked paint film after overnight aging of finished coils.
Ribbing – (See Roping.)
Roll former - An apparatus that forms a continuous strip of painted metal into various shapes by a series of revolving metal wheels or rolls.
Roll Grinder - A special lathe used in grinding down applicator rolls.
Roping - Longitudinal streaks that do not flow out on a painted strip. This is sometimes referred to as Ribbing.
Seal Coat - Refers to the application of a clear coat.
Shear - The viscous force acting parallel to the strip at the point where the applicator roll meets the strip on a roller coater. Shear also occurs at all roll-to-roll contact points. Can also refer to metal cutting equipment.
Sheen - A measure of gloss at low angles usually 85 degrees from the vertical.
Silicone - Addition of silicone to modify the polyester resin or acrylic resign enhance gloss/color retention. These are referred to as siliconized polyesters.
Single Coat - Application of one coating at a specified dry film thickness directly over system: conversion coating and substrate.
Skipping - An irregular paint application usually occurring when improper contact is made between the applicator roll and the strip. (See Starving Out.)
Slitting - A process by which a wide strip is slit or cut into narrower widths.
Slopping Over - A term used when some of the finish used on the top side of a continuous strip finds its way to the bottom side.
Solvent - A solution that is capable of dissolving or solvating another substance.
Slow Solvent - A solvent that does not evaporate quickly.
Solution Vinyl - Low volume solid coating that creates high VOC,s in the coil process. Polyester technology has made this resin almost obsolete for coil coating. It is readily substituted with a polyester system.
Split Coat - The application of the same coating at two different coating stations on the coil line. This is generally done to build dry film thickness.
Spool – (See Uncoiler.)
Stalling - Stoppage of the applicator roll as a result of being too tight against the strip. Usually results in wearing a flat spot on the applicator roll.
Starter Strip Night Strip - A length of metal threaded through a line after shutdown. This is used repeatedly with new coils attached to thread the new coil through the line.
Starving Out - Irregular film thickness applied to the strip usually the result of insufficient liquid level in the coating pan, adverse reaction of the coating to the shear actions, improper speed ratio between strip and coating rolls or improper wetting of the rolls by the coating material.
Stitcher - A stapling device used to connect the end of one coil to the beginning of another coil.
Streaking - A type of floating that forms a longitudinal pattern visible as a variation in gloss or color.
Substrate – The metal strip that is fed to the coil coating process and receives the paint coating.
Two Coat - Typically an application of a primer and topcoat back coat over the system; conversion coating and substrate. It may refer to any two-coat combination.
Tandem Line - A roller coat line with two coaters and ovens capable of applying and baking two coats of paint to each side (i.e. primer and topcoat) prior to recoiling.
Test Strip - A sample length usually 50 to 150 linear feet of subject metal stitched between two starter strips and coated so as to check paint color, thickness, cure, etc.
Thermoplastic - Capable of becoming soft or plastic upon the application of heat. Pertains to a fuse film, which softens when heated then regains its original properties on cooling.
Thermosetting - Having no tendency to soften upon heating. Pertains to a cured or converted film, which retains its hardness when heated.
Thinner - A liquid that is mixed into an organic to reduce viscosity for application. The use of a thinner in a coating to change viscosity is referred to as reduction.
Three Coat - Application of any three coat combination (i.e. base coat, ink and system; clear).
Tin Mill Black Plate – A thin (under .015 inches thick) metal substrate that consists of cold rolled carbon steel with no metallic coating.
Top Coat - The top layer of coating that has been applied over another layer of coating (i.e. a primer) on a two-coat system. The dry film thickness applied is to be specified. Typically, the dry film thickness is not less than 0.60 mls. For exterior primed applications.
Trough - (See Pan.)
Transfer Roll - The roll between the pick-up and applicator rolls, which transfer the paint conversion coating or other liquids to the applicator roll.
Treatment Section - This is a conventional immersion of iron phosphate, zinc phosphate, chromium chromate and final chromate rinse.
Wash Coat – A thin coating applied to the back or unexposed side of coated strip. It functions the same as backer coat except that it is not closely controlled for color, gloss or applied film. It is usually a functional coating that is applied for reasons such as appearance, durability, lubrication for roll forming, etc.
Water Cooler or Quench - The mechanism used to apply water to a painted strip directly after leaving the oven to cool the strip prior to recoiling. Means for drying before recoiling are provided.
Zinc Phosphate - A non-metallic, crystalline structure that provides an inert, non-conductive bond between the zinc coated metal substrate and the organic coating. This is considered a conversion coating. The major components for the zinc phosphate coating are soluble metallic zinc, phosphoric acid, soluble metallic nickel and soluble inorganic nitrates. The zinc phosphate coating requires a conditioning bath prior to its application. This conditioning bath promotes the formation of a dense and finely structured crystalline zinc phosphate coating.