The Language of Finishing: Paint and Coatings Glossary C–D

Practical definitions covering coating application, corrosion protection, curing, inspection, dry-film thickness, equipment, and common defects.

This installment of The Language of Finishing covers industry terms beginning with the letters C and D. Definitions are written for coating applicators, inspectors, contractors, finishing-line operators, maintenance personnel, specifiers, equipment professionals, and others involved in applied coatings.

Where a term is used differently among automotive refinishing, OEM finishing, aerospace, protective coatings, powder coating, floor coatings, roof coatings, linings, and other sectors, additional context is provided.

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C

Calibration

Industry areas: Inspection, Quality Control, Application Equipment

Calibration is a controlled process in which an instrument’s readings are compared with traceable reference values over its operating range. Calibration is normally performed by the equipment manufacturer, an authorized service center, or a qualified laboratory.

Calibration should not be confused with field verification or adjustment. A coating inspector may verify an instrument’s accuracy and adjust it for the substrate, but that does not necessarily constitute calibration.

Catalyst

Industry areas: Automotive Refinish, Aerospace, OEM, Protective Coatings, Floor Coatings

A catalyst is a substance that changes or accelerates a chemical reaction. In everyday coating language, the word is sometimes used broadly for an activator, hardener, or curing component, even when that component chemically participates in the reaction.

Always follow the terminology and mixing ratio supplied by the coating manufacturer. Catalyst, activator, converter, and hardener should not automatically be treated as interchangeable products.

Cathodic Disbondment

Industry areas: Pipeline Coatings, Tank Coatings, Buried Structures, Marine

Cathodic disbondment is the loss of coating adhesion associated with conditions produced by a cathodic-protection system at a coating defect or holiday.

The coating may separate from the substrate around the damaged area even though cathodic protection is reducing corrosion at the exposed metal. Pipeline and buried-service coatings may be evaluated for resistance to this condition.

Cathodic Electrocoat

Industry areas: E-Coat, Automotive OEM, Industrial OEM

Cathodic electrocoat is an electrodeposition process in which the workpiece functions as the cathode. It is frequently abbreviated as CED, meaning cathodic electrodeposition.

Cathodic E-coat is widely used as a corrosion-resistant primer on automotive bodies, components, appliances, agricultural equipment, and other manufactured metal products. Performance depends on pretreatment, bath control, electrical conditions, rinsing, and cure.

CED — Cathodic Electrodeposition

CED is the abbreviation for cathodic electrodeposition. Coating particles are electrically deposited from a water-based bath onto a conductive workpiece serving as the cathode.

The deposited film is normally rinsed to recover drag-out material and then baked to develop its intended properties.

Chalking

Industry areas: Architectural, Protective Coatings, Roof Coatings, Automotive, OEM

Chalking is the formation of a loose, powdery material on a coating surface as the binder degrades and pigment or extender particles become exposed.

Chalking is commonly associated with ultraviolet exposure and weathering. It should be distinguished from dust, overspray, process residue, salt, and other surface contamination.

Checking

Industry areas: Architectural, Wood Finishing, Protective Coatings, Automotive

Checking consists of fine, shallow breaks in the surface of a coating. The lines generally do not initially penetrate through the entire coating system.

Checking can indicate aging, loss of flexibility, excessive film thickness, or repeated expansion and contraction. Continued deterioration may allow checking to develop into deeper cracking.

Chemical Resistance

Industry areas: Linings, Floors, OEM, Aerospace, Protective Coatings

Chemical resistance is a coating’s ability to withstand contact with specified chemicals without unacceptable softening, swelling, discoloration, blistering, loss of adhesion, dissolution, or other deterioration.

Resistance depends on the chemical, concentration, temperature, contact time, cleaning method, coating thickness, cure, and whether exposure is continuous, intermittent, or by splash and spill. ASTM D1308 addresses the effects of household chemicals on clear and pigmented coating systems.

Chip Resistance

Industry areas: Automotive Refinish, Automotive OEM, Rail, Aerospace

Chip resistance is a coating system’s ability to withstand impact from gravel, stones, debris, or other small objects without excessive chipping or loss of adhesion.

Chip resistance is influenced by the substrate, pretreatment, primer, coating flexibility, film thickness, cure, temperature, and total coating-system design.

Chromate Conversion Coating

Industry areas: Aerospace, Aviation, Aluminum Finishing, OEM

A chromate conversion coating is a chemically produced surface treatment used on aluminum, zinc, magnesium, and certain other metals to improve corrosion resistance and provide a base for subsequent coating.

Because chromates present environmental and health concerns, non-chromate alternatives are increasingly used. The selected pretreatment must meet the applicable specification and coating-system requirements.

Circulation System

Industry areas: OEM, Industrial Finishing, Automatic Spray, E-Coat

A circulation system continuously or intermittently moves coating through supply and return piping. It helps maintain consistent material condition, temperature, suspension, color availability, and pressure at application stations.

Pump selection, pipe size, flow velocity, filtration, agitation, back-pressure control, and coating shear sensitivity all affect system performance.

Cleanliness

Industry areas: Surface Preparation, Inspection, All Coating Sectors

Cleanliness describes the degree to which unwanted materials have been removed from a substrate or coating surface. Contaminants may include oil, grease, dirt, dust, rust, mill scale, moisture, soluble salts, release agents, polishing compounds, and deteriorated coating.

A surface can look clean but still contain invisible contamination. The required preparation standard and test methods should be defined before coating.

Clearcoat

Industry areas: Automotive Refinish, Automotive OEM, Aerospace, Wood Finishing

A clearcoat is a transparent or substantially transparent coating applied over a colored, decorative, or functional layer. It may provide gloss, depth, weather resistance, chemical resistance, abrasion resistance, or protection for the underlying finish.

In automotive basecoat-clearcoat systems, the basecoat primarily provides color and effect while the clearcoat provides much of the gloss and environmental protection.

Coat

A coat is a single continuous layer of coating produced during one application sequence. A complete coating system may contain a primer coat, one or more intermediate coats, and a finish coat.

Multiple spray passes used to form one continuous layer do not necessarily constitute multiple coats.

Coating

A coating is a material applied to a surface to form a film or layer that provides protection, decoration, identification, or a specialized function.

Coatings may be liquid, powder, mastic, cementitious, metallic, or otherwise applied. Their functions may include corrosion protection, chemical resistance, waterproofing, fire protection, electrical insulation, color, texture, or wear resistance.

Coating Failure

Coating failure occurs when a coating or coating system no longer provides an intended property or fails to meet an established requirement.

Failure may involve adhesion, corrosion protection, appearance, chemical resistance, thickness, cure, flexibility, or another property. A defect is not automatically a failure unless it prevents the coating from meeting its intended requirement.

Coating System

A coating system is the complete combination of surface preparation, pretreatment, primer, intermediate coats, finish coats, stripe coats, and other specified layers used on a substrate.

System performance depends on the compatibility and proper application of every layer. A high-performance topcoat cannot compensate for a contaminated substrate or failing primer.

Cohesion

Cohesion is the internal strength that holds a material together. In coating-failure analysis, cohesive strength may refer to the internal strength of a coating layer, adhesive, or substrate.

Cohesion differs from adhesion, which describes attachment between different materials or layers.

Cohesive Failure

Cohesive failure occurs within a material rather than at the interface between two different materials. Examples include separation within a coating layer, within an adhesive, or within weak concrete beneath a floor coating.

Pull-off test reports should identify where the failure occurred instead of recording only the numerical result.

Color Match

Industry areas: Automotive Refinish, OEM, Aerospace, Architectural, Wood Finishing

Color match describes how closely an applied or prepared coating agrees with a target color under specified viewing conditions.

Substrate color, film thickness, application method, metallic orientation, curing conditions, gloss, texture, lighting, and viewing angle can influence the perceived match.

Color Retention

Color retention is a coating’s ability to maintain its original or specified color during exposure. Ultraviolet radiation, heat, chemicals, weather, pigments, coating type, and service conditions can affect color retention.

Color retention and gloss retention are related appearance properties, but one may change without the other.

Commercial Blast Cleaning

Industry areas: Protective Coatings, Structural Steel, Marine, Industrial Maintenance

Commercial blast cleaning is a defined degree of abrasive blast cleaning for steel. It is more thorough than industrial or brush-off blast cleaning but permits limited staining under the governing standard.

It is commonly associated with SSPC-SP 6/NACE No. 3. The complete current standard should be consulted for its official requirements.

Compressed-Air Quality

Industry areas: Spray Application, Abrasive Blasting, Powder Coating

Compressed-air quality describes the cleanliness, dryness, temperature, and suitability of compressed air for its intended use. Oil, water, rust, dirt, and other contamination can damage equipment or create coating defects.

ASTM D4285 provides a field practice for indicating oil or water in compressed air used for blast cleaning, air cleaning, and coating application.

Conductive Coating

Industry areas: Electrostatics, Electronics, Floors, Specialty Coatings

A conductive coating allows electrical current or charge to pass through or across the applied film to a specified degree.

Conductive coatings may be used for static dissipation, electromagnetic shielding, electrical grounding, heated surfaces, sensors, or electrostatic application to otherwise nonconductive substrates.

Conductivity

Industry areas: Electrostatic Application, E-Coat, Pretreatment, Water Quality

Conductivity is a material’s ability to conduct electrical current. It can be important when evaluating liquid coatings for electrostatic spray, process water, pretreatment baths, E-coat baths, substrates, and grounding conditions.

The units, temperature, test method, and material being measured must be identified when reporting conductivity.

Contamination

Industry areas: All Coating Sectors

Contamination is unwanted material present on a substrate, in a coating, in compressed air, or within the application environment. Contaminants may be visible or invisible.

Common examples include oil, grease, silicone, dust, moisture, soluble salts, fibers, polishing compounds, mold-release agents, incompatible coating, and process residue.

Containment

Industry areas: Abrasive Blasting, Protective Coatings, Lead-Paint Removal, Marine

Containment is a temporary or permanent enclosure and control system used to limit the release of dust, abrasive, debris, overspray, fumes, or hazardous materials from a work area.

Containment design may include sheeting, framing, ventilation, negative pressure, filtration, airlocks, waste handling, and worker-protection measures.

Conversion Coating

Industry areas: OEM, Automotive, Aerospace, Powder Coating, Metal Finishing

A conversion coating is a surface layer formed by a chemical or electrochemical reaction with the metal substrate. Examples include phosphate, chromate, zirconium, and certain oxide treatments.

Conversion coatings can improve corrosion resistance and coating adhesion. They are different from ordinary deposited paint films because the treatment chemically modifies the surface.

Corrosion

Industry areas: Protective Coatings, Marine, Aerospace, Rail, OEM, Pipelines

Corrosion is the deterioration of a material, usually a metal, through chemical or electrochemical interaction with its environment.

Coatings help control corrosion by isolating the substrate, inhibiting the corrosion reaction, supplying sacrificial protection, or combining multiple protective mechanisms.

Corrosion Inhibitor

A corrosion inhibitor is a substance or component used to reduce the rate of corrosion. Inhibitors may be incorporated into primers, process solutions, temporary protective materials, cooling systems, or storage treatments.

The term does not identify a specific protection mechanism or prove suitability for a particular environment.

Corrosion Undercutting

Corrosion undercutting is corrosion that spreads beneath a coating from a holiday, scratch, edge, scribe, or other point of exposure.

The coating may remain visually intact above part of the affected area while adhesion is being lost underneath. ASTM D1654 addresses evaluation of coated specimens after corrosive exposure, including loss of adhesion and corrosion associated with a scribe.

Coverage

Coverage may describe the area coated by a specified quantity of material or the degree to which the coating uniformly covers and hides the substrate.

Theoretical coverage is calculated from volume solids and target film thickness. Actual coverage is reduced by overspray, surface profile, equipment losses, mixing waste, retained material, and application technique.

Cracking

Industry areas: All Coating Sectors

Cracking is the formation of visible breaks in a coating film. Cracks may affect only one layer or penetrate through the entire coating system to the substrate.

Possible causes include excessive thickness, incompatibility, substrate movement, rapid drying, improper cure, aging, thermal cycling, and loss of flexibility.

Cratering

Industry areas: Automotive, OEM, Powder Coating, Wood Finishing

Cratering is the formation of small, bowl-shaped depressions in a coating surface. A crater may expose an underlying layer or have a raised outer edge.

Surface-tension differences caused by silicone, oil, water, incompatible material, dirty compressed air, or environmental contamination are common contributors.

Cross-Cut Adhesion Test

A cross-cut adhesion test evaluates coating adhesion by cutting a lattice pattern through the film, applying specified tape, removing the tape, and rating the amount of coating detached.

The result depends on coating thickness, spacing, substrate, cutting tool, tape, technique, and governing method. It is a rating procedure rather than a direct measurement of adhesion force. ASTM D3359 includes a cross-cut tape method for appropriate coating systems on metallic substrates.

Crosslinking

Crosslinking is the formation of chemical bonds between molecular chains as certain coatings cure. Crosslinking can develop hardness, solvent resistance, chemical resistance, heat resistance, and other film properties.

Improper mixing, insufficient temperature, incorrect bake time, expired material, or unsuitable environmental conditions may prevent complete crosslinking.

Cure

Cure is the process by which an applied coating develops its intended film properties through chemical reaction, coalescence, solvent or water loss, heat, radiation, oxidation, or a combination of mechanisms.

A coating can be dry to the touch without being fully cured. Full cure may be required before immersion, chemical exposure, assembly, heavy traffic, or return to service.

Cure Schedule

A cure schedule defines the time, temperature, humidity, radiation exposure, or other conditions required for a coating to develop specified properties.

For baked coatings, the schedule may be based on part-metal temperature rather than oven-air temperature. Field-applied coatings may require additional curing time when temperatures are near the lower application limit.

Curing Agent

A curing agent is a reactive component mixed with certain coatings to produce the intended cure. It may also be called a hardener, converter, or activator.

The correct component, mixing ratio, induction time, pot life, and application conditions are essential. A curing agent from one product should never be substituted into another system without written manufacturer approval.

Curtain Coating

Industry areas: Wood Finishing, Flat-Panel Coating, OEM

Curtain coating passes a flat workpiece through a continuous falling curtain of liquid coating. It can provide high production and uniform coverage on suitable products.

Coating viscosity, flow rate, conveyor speed, curtain stability, filtration, and workpiece geometry must be controlled.

Cyclic Corrosion Testing

Industry areas: Automotive OEM, Aerospace, Rail, Protective Coatings

Cyclic corrosion testing exposes coated specimens to repeating stages that may include salt solution, humidity, drying, temperature changes, and controlled atmospheric conditions.

The objective is generally comparative evaluation of coating systems. Results should not be converted directly into years of field service unless a reliable correlation has been established.

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D

Deadman Control

Industry areas: Abrasive Blasting, Waterjetting

A deadman control is a safety device that requires continuous operator activation to keep blasting or waterjetting equipment operating. Releasing the control is intended to stop abrasive or water flow and depressurize or control the system as designed.

The control must not be tied down, bypassed, or defeated.

Decorative Coating

A decorative coating is applied primarily to provide color, gloss, texture, pattern, or another visual effect. Many decorative coatings also provide protection, cleanability, or weather resistance.

The term describes the coating’s principal purpose rather than a particular chemistry or application method.

Defect

A defect is an irregularity or departure from the intended appearance, structure, application, or performance of a coating.

Examples include runs, sags, craters, pinholes, dry spray, blistering, cracking, uneven color, and contamination. A defect becomes a nonconformance when it violates an established requirement.

Degreasing

Industry areas: Surface Preparation, OEM Pretreatment, Maintenance Painting

Degreasing removes oil, grease, machining fluid, fingerprints, and similar organic contamination from a surface.

Methods may include alkaline cleaning, solvent cleaning, detergent washing, vapor degreasing, emulsifying cleaners, or other approved processes. Abrasive blasting should not be relied upon to remove heavy oil or grease.

Deionized Water

Industry areas: Pretreatment, E-Coat, Automotive OEM, Aerospace, Cleaning

Deionized water has had a substantial portion of its dissolved ions removed. It is frequently abbreviated as DI water.

DI water is commonly used in final rinses, E-coat systems, pretreatment processes, coating reduction, equipment cleaning, and other operations where dissolved minerals could leave residue or interfere with performance.

Delamination

Industry areas: All Coating Sectors

Delamination is the separation of one layer from another within a coating system or the separation of the coating system from the substrate.

It may result from contamination, poor preparation, moisture, incompatible materials, exceeded recoat windows, corrosion, excessive stress, or incomplete cure.

Density

Density is mass per unit volume. In the coatings industry, it may be expressed as pounds per gallon, kilograms per liter, or another appropriate unit.

Density affects material handling, coverage calculations, mixing, pumping, spray behavior, and conversion between weight and volume.

Desiccant Air Dryer

Industry areas: Compressed Air, Powder Coating, Instrument Air, Spray Application

A desiccant air dryer removes water vapor from compressed air by passing it through a moisture-attracting material. It can produce lower dew points than many refrigerated dryers.

Desiccant condition, airflow, pressure, regeneration, filtration, and maintenance affect dryer performance.

Destructive Dry-Film Thickness Measurement

Industry areas: Coating Inspection, Protective Coatings, Multicoat Systems

Destructive thickness measurement requires cutting, drilling, grinding, or otherwise penetrating a coating so its cross-section can be examined.

It may allow an inspector to distinguish individual layers that a conventional magnetic or eddy-current gauge reads only as total thickness. The test area normally requires repair. ASTM D4138 addresses cross-sectioning practices for protective coating systems.

Detackification

Industry areas: Liquid Spray Booths, Water-Wash Booths, Automotive OEM

Detackification is a treatment used to reduce the stickiness of paint overspray captured in a water-wash spray-booth system.

Proper chemical control helps separate paint solids from booth water, reduce deposits, control foam, and support sludge removal.

Dew Point

Industry areas: Field Application, Inspection, Industrial Coatings

The dew point is the temperature at which air becomes saturated with water vapor and condensation begins to form under the existing conditions.

Coating specifications commonly require the substrate temperature to remain a stated amount above the dew point. Air temperature, relative humidity, surface temperature, and dew point should be measured and recorded at the work location. ASTM E337 addresses humidity measurement using psychrometers.

DFT — Dry-Film Thickness

DFT means dry-film thickness, the thickness of a coating after it has dried or cured sufficiently for measurement.

DFT is commonly expressed in mils or micrometers. One mil equals 0.001 inch and approximately 25.4 micrometers.

Diaphragm Pump

Industry areas: Liquid Coating Transfer, Circulation, Spray Equipment

A diaphragm pump moves fluid through the reciprocating action of flexible diaphragms and check valves. Air-operated double-diaphragm pumps are commonly used to transfer, supply, or circulate coatings and related fluids.

Diaphragm pumps are not automatically appropriate for every spray technology. Required pressure, flow, pulsation control, coating shear sensitivity, solvent compatibility, and solids content must be considered.

Dielectric Strength

Industry areas: Electrical Insulating Coatings, Linings, Specialty OEM

Dielectric strength is a material’s ability to resist electrical breakdown under an applied electric field. It is commonly reported as voltage per unit thickness.

Film thickness, defects, moisture, temperature, cure, and test method affect the result.

Differential Pressure

Industry areas: Spray Booths, Filters, Powder Recovery, Ventilation

Differential pressure is the difference in pressure between two points. In finishing systems, it is commonly used to monitor filter loading, booth balance, powder collectors, air-handling equipment, and containment pressure.

A changing pressure differential can indicate dirty filters, restricted airflow, leakage, or another system condition requiring investigation.

Diluent

Industry areas: Liquid Coatings, Application Adjustment

A diluent is a liquid used to reduce viscosity or adjust the application properties of a coating. Depending on the product, it may be called thinner, reducer, solvent, or water.

Only the type and amount permitted by the coating manufacturer should be used. Excessive or incorrect dilution can affect volume solids, film build, VOC content, atomization, sag resistance, drying, and cure.

Dip Coating

Industry areas: OEM, Metal Finishing, Wood Finishing, Specialty Coatings

Dip coating immerses a workpiece in liquid coating and then withdraws it under controlled conditions. Film thickness and appearance are influenced by coating viscosity, withdrawal speed, drainage, part geometry, temperature, and cure.

Dip coating differs from electrodeposition because ordinary dipping does not use an electrical field to deposit the film.

Direct-to-Metal Coating

Industry areas: Industrial Maintenance, OEM, Agricultural Equipment

A direct-to-metal coating, commonly abbreviated DTM, is designed to be applied directly to a properly prepared metal substrate without a separate conventional primer in specified exposures.

DTM does not mean direct-to-dirt, direct-to-rust, or direct-to-contamination. Surface preparation and environmental requirements still apply.

Dirt Nib

Industry areas: Automotive Refinish, Aerospace, OEM, Wood Finishing

A dirt nib is a small raised imperfection caused by dust, fiber, dried coating, or another particle trapped in the wet film.

Control depends on booth cleanliness, filtration, clothing, surface preparation, compressed-air quality, material filtration, equipment maintenance, and housekeeping.

Dolly

Industry areas: Adhesion Testing, Coating Inspection

A dolly is a loading fixture bonded to the coated surface during a pull-off adhesion test. The tester applies force perpendicular to the surface until separation occurs or the specified load is reached.

Dolly size, adhesive, preparation, curing time, cutting procedure, tester type, loading rate, and failure location must be documented.

Downdraft Spray Booth

Industry areas: Automotive Refinish, Aerospace, Industrial Finishing

A downdraft spray booth moves filtered air downward through the working area toward exhaust openings at or near floor level.

When properly designed and balanced, downdraft airflow can carry overspray away from the work and operator. Booth type alone does not establish compliance or guarantee finish quality.

Drawdown

Industry areas: Quality Control, Color Evaluation, Coating Comparison

A drawdown is a controlled film applied to a test card, panel, or other surface using an applicator bar, blade, or similar device.

Drawdowns are used to compare color, hiding, gloss, appearance, drying, compatibility, or other coating properties under controlled conditions.

Dry Fall

Industry areas: Commercial Painting, Industrial Maintenance, Warehouses

Dry-fall coating is formulated so that overspray droplets are intended to dry to a removable dust within a specified fall distance under stated temperature, humidity, ventilation, and application conditions.

The term does not mean that all overspray will always be harmless or easily removed. Nearby property should still be protected, and the manufacturer’s limitations must be followed.

Dry-Film Thickness

Industry areas: All Coating Sectors

Dry-film thickness is the thickness of an applied coating after drying or cure. It is one of the most important variables affecting hiding, appearance, adhesion, flexibility, cure, corrosion protection, and service life.

ASTM D7091 addresses nondestructive measurement using magnetic and eddy-current gauges on appropriate metal substrates. The governing specification determines sampling frequency and acceptance criteria.

Dry Spray

Industry areas: Liquid Spray, Automotive, Protective Coatings, OEM

Dry spray is a rough, poorly coalesced deposit produced when atomized coating loses too much liquid before reaching or flowing on the surface.

Possible causes include excessive gun distance, high atomizing pressure, fast solvent, high temperature, excessive airflow, low fluid flow, or poor spray technique.

Dry-to-Handle

Dry-to-handle describes a stage at which a coated item can be carefully handled without unacceptable damage under the conditions defined by the coating manufacturer.

It does not necessarily mean the coating is ready for packaging, assembly, chemical exposure, heavy service, immersion, or final adhesion testing.

Dry-to-Touch

Dry-to-touch describes a stage at which a coating surface no longer feels wet or transfers material under a defined light-touch evaluation.

A coating can be dry to the touch while remaining soft, solvent-rich, uncured, or unsuitable for recoating or service.

Drying Oven

Industry areas: OEM, Automotive, Powder Coating, E-Coat

A drying oven supplies controlled heat to remove water or solvent, warm parts, or complete a specified drying stage. Some ovens also cure or fuse coatings, but drying and curing are not always the same operation.

Oven airflow, temperature uniformity, exhaust, part loading, product mass, and line speed influence performance.

Drying Time

Drying time is the elapsed time required for a coating to reach a defined stage of dryness under specified conditions.

Examples include dust-free, tack-free, dry-to-touch, dry-to-handle, recoat, and full-cure times. A drying time is meaningful only when the test condition and dry stage are identified.

Dual-Component Coating

Industry areas: Protective Coatings, Automotive, Aerospace, Floors, Linings

A dual-component coating, also called a two-component or plural-component coating, requires two separate components to be mixed before application.

The components must be combined at the specified ratio. Once mixed, the material normally has a limited pot life. Some plural-component equipment mixes the materials only moments before they reach the spray gun.

Dust Contamination

Dust contamination is unwanted particulate matter on a prepared surface, between coats, or embedded in the finished film.

Dust may reduce adhesion, create roughness, produce visible defects, contaminate color, or

Tags: coatings glossary C-D, coating terminology, coating cure, corrosion protection, coating defects, dry film thickness, dew point testing, coating delamination, paint application terms