Powder Coating and Painting Industry Terminology

Abrasive Blasting

Surface preparation process that propels media (e.g., steel grit, aluminum oxide, glass bead) to clean and create an anchor profile for coating adhesion.

Used to remove rust and mill scale before coating; Specifying a 2–3 mil anchor profile for better adhesion; Switching from glass bead to aluminum oxide to increase profile depth.

Adhesion

The strength of the bond between the coating and the substrate, influenced by surface preparation, pretreatment, cure, and contamination.

Achieved 5B adhesion on ASTM D3359 crosshatch; Adhesion failures traced to oil contamination on the welds; Improved adhesion after adding a zirconium conversion stage.

Bake Schedule

The specified time-at-temperature required to properly cure a coating, typically defined by metal temperature and dwell time.

Cured at 190°C metal temperature for 12 minutes; Oven recipe adjusted to compensate for thicker castings; Data logger confirmed the bake schedule meets the powder’s TDS.

Blistering

Dome-shaped coating defects caused by internal pressure from entrapped moisture, solvents, or gases, often linked to poor pretreatment or outgassing.

Blisters appeared over laser-cut edges due to trapped oils; Salt-spray blisters initiated along the scribe; Reduced blistering after improving rinse quality.

Color Matching

The process of achieving a specified color using standardized systems and instruments (e.g., spectrophotometer, CIE L*a*b*, RAL), balancing pigments, gloss, and texture.

Delta E below 1.0 versus the RAL standard; Adjusted tint to match the customer’s legacy color chip; Spectrophotometer readings verified batch-to-batch consistency.

Conversion Coating

A chemical pretreatment that converts the metal surface to a thin, protective layer (e.g., zinc/iron phosphate, zirconium, chromate) to enhance adhesion and corrosion resistance.

Switched from zinc phosphate to zirconium to cut sludge; Improved adhesion after adding a silane seal; Achieved salt-spray targets with a 5-stage conversion line.

DFT (Dry Film Thickness)

The thickness of the cured coating, typically expressed in mils (thousandths of an inch) or microns, measured by magnetic or eddy current gauges.

Measured 2.8 mils with a magnetic gauge; Customer spec requires 60–80 microns; Increased film build on edges with a second pass.

Degassing

A process or formulation strategy to release entrapped gases from substrates (e.g., castings, galvanized steel) before or during curing to avoid pinholes.

Pre-baked castings at 200°C to drive off porosity gases; Chose a degassing-grade powder for galvanized parts; Pinholes reduced after adding a preheat step.

Edge Coverage

The ability of a coating to build sufficient film thickness over sharp edges and corners, which tend to thin due to electrostatic and flow effects.

Chamfered sharp corners to improve coverage; Lowered kV to reduce back-ionization on edges; Applied a zinc-rich primer to build film on edges.

Electrostatic Spray

Application method where powder particles are electrically charged (corona or tribo) and attracted to a grounded part, improving deposition and wrap.

Set the gun to 70 kV for better wrap; Switched to a tribo gun for recessed features; Improved transfer efficiency after fixing the ground.

Faraday Cage Effect

Difficulty depositing powder into recessed or inside corners due to electric field shielding, causing thin film in those areas.

Lowered kV and moved closer to spray into tight corners; Added auxiliary electrodes to reach deep recesses; Rotated parts to change the line of sight.

Flow and Leveling

The coating’s ability to melt, flow, and level during cure, affecting smoothness, orange peel, and gloss.

Orange peel reduced after increasing oven temperature; Changed to a smoother-flowing formula for Class A surfaces; Shorter gel time reduced leveling and increased texture.

Gel Time

The time it takes for a powder to transition from melt to gel at a specified temperature, used to characterize cure kinetics and predict flow.

QC recorded 60 seconds at 200°C; Longer gel time improved leveling but hurt edge coverage; Batch-to-batch gel-time variation flagged for review.

Grounding

Providing a low-resistance path to earth for parts, racks, and operators to enhance electrostatic deposition and reduce defects like back-ionization.

Measured rack resistance under 1 megaohm; Cleaned hooks improved first-pass transfer efficiency; Added more ground points to long extrusions.

HVLP (High Volume Low Pressure)

An air-atomizing spray method for liquid paints that uses high air volume at low pressure to improve transfer efficiency and reduce overspray/VOCs; often used alongside powder operations.

Switched to HVLP guns to reduce liquid paint overspray; HVLP used for wet touch-up on powder-coated parts; Trained operators on HVLP fan control for edge work.

Impact Resistance

The coating’s ability to withstand sudden mechanical force without cracking or delaminating, commonly measured by Gardner impact.

Passed 160 in-lb reverse impact per ASTM D2794; Cracking at the bend failed impact resistance; Selected a tougher resin to improve impact performance.

Infrared (IR) Oven

A curing technology that uses radiant infrared energy to rapidly heat parts, often combined with convection ovens for efficient curing.

Used IR boost to gel powder before the convection zone; Shortened cure time on heavy parts with IR panels; IR preheat improved outgassing on castings.

JIT (Just-in-Time)

A production and inventory strategy that supplies parts as they are needed to minimize WIP, inventory, and lead times.

Sequenced colors to minimize changeovers and WIP; JIT deliveries aligned with the OEM’s build schedule; Reduced inventory using Kanban for powder replenishment.

KPI (Key Performance Indicator)

Quantifiable metrics used to evaluate operational performance, such as OEE, first-pass yield, scrap rate, and on-time delivery.

Tracked first-pass yield and on-time delivery weekly; OEE improved after reducing unplanned downtime; DPMO on cosmetic defects dropped 40%.

Lean Manufacturing

A methodology focused on eliminating waste and improving flow using tools like 5S, SMED, and value stream mapping.

Implemented 5S at the spray booth; SMED reduced color change time from 30 to 10 minutes; Mapped the value stream to cut travel distance.

Line Speed

The conveyor rate, often measured in feet per minute, that determines throughput and dwell time in wash and oven zones.

Increased to 6 fpm after confirming cure; Slowed the line for thicker weldments; Adjusted speed to hit the target oven dwell time.

MDF Powder Coating

Applying specialized low-temperature or UV-curable powders to medium-density fiberboard and other heat-sensitive substrates.

Used low-temperature powder and IR/UV cure for MDF doors; Controlled board moisture before coating; Reduced fiber raise with a sealer primer.

Masking

The use of tapes, caps, plugs, and fixtures to shield areas from coating or preserve electrical ground contact.

Applied silicone caps to protect threaded holes; Used high-temp tape for grounding points; Designed custom silicone plugs for complex geometries.

Non-Chrome Conversion Coating

Chrome-free pretreatment chemistries (e.g., zirconium, titanium, silane) that provide adhesion and corrosion protection without hexavalent chromium.

Replaced hex-chrome with zirconium to meet EHS goals; Maintained corrosion resistance with a silane seal; Reduced sludge and water usage after conversion.

OEM Specifications

Performance and process requirements defined by Original Equipment Manufacturers for coated parts, including test protocols, documentation, and traceability.

Coating qualified to the automaker’s spec; Verified salt spray and impact per the OEM standard; Documented lot traceability for OEM audits.

Outgassing

The release of gases from a substrate during cure that can cause pinholes or craters, commonly seen in castings and galvanized steel.

Pinholes on galvanized due to trapped hydrogen; Pre-bake reduced outgassing defects on cast iron; Selected an outgassing-forgiving polyester.

PCI (Powder Coating Institute)

An industry association offering education, certification, and best-practice resources for powder coating operations.

Used PCI training for new operators; Pursued PCI Certification to validate best practices; Followed PCI guidelines for grounding and safety.

Phosphate (Zinc/Iron Phosphate)

Common conversion coatings that form crystalline layers on steel to improve corrosion resistance and paint adhesion; zinc is heavier-duty, iron is simpler/lower cost.

Moved from iron to zinc phosphate for higher corrosion resistance; Controlled phosphate weight via titration; Addressed sludge buildup in the phosphate stage.

Pigments

Finely ground colorants dispersed in the binder to provide color, opacity, and durability; selection affects UV stability, heat resistance, and cost.

Switched to inorganic pigments for better UV stability; Adjusted TiO2 level to improve hiding; Evaluated heat-stable pigments for high-bake cycles.

Pretreatment

The sequence of cleaning, rinsing, conversion coating, and sealing steps that prepare the substrate for coating.

Upgraded from a 3-stage to a 5-stage system; Optimized cleaner concentration via titration; Added RO water for final rinse quality.

QA/QC (Quality Assurance and Control)

Systems and procedures to ensure coatings meet specifications, including inspections, testing, documentation, and corrective actions.

Performed DFT checks every hour; Implemented cure tests for each color change; Documented lot traceability and test results for audits.

QUV Accelerated Weathering

Laboratory exposure using UV and condensation cycles (e.g., ASTM G154) to evaluate weathering durability of coatings.

Ran 1,000 hours per ASTM G154; Noted gloss loss faster in reds than whites; Used QUV data to qualify exterior-grade powders.

RAL Colors

A widely used European color standard system that provides consistent, codified shades for specifying and matching colors.

Ordered powder matched to RAL 9016; Customer specified RAL 7021 for cabinets; Verified color against the RAL fan deck.

Recoat Window

The allowable time and condition (e.g., gel-in-gel, partial cure, or after scuffing a full cure) for applying an additional coat to ensure adhesion.

Applied the second coat gel-in-gel for better intercoat adhesion; Scuffed a fully cured part before recoating; Recoat window shortened at higher bake temperatures.

Salt Spray (ASTM B117)

A standardized corrosion test exposing panels to a salt fog environment to compare system performance; not a direct predictor of field life.

Met 1,000 hours to first scribe rust with primer/topcoat; Used salt-spray as a comparative test for pretreat changes; Failures traced to underfilm corrosion at cut edges.

Substrate

The underlying material being coated (e.g., steel, aluminum, galvanized, magnesium, zinc die-cast, MDF), each with unique prep and cure needs.

Processed mixed loads of aluminum and CRS; Adjusted cure for thick steel weldments; Selected a degassing formula for die-cast zinc.

Surface Profile

The micro-roughness/anchor pattern on a surface, typically created by blasting, that promotes mechanical adhesion.

Specified a 2 mil profile for heavy-duty epoxy primer; Measured Ra to confirm blast consistency; Smoothed laser burrs to reduce shadowing and pinholes.

Tape Test (ASTM D3359)

A quick adhesion test using crosshatch or X-cut and pressure-sensitive tape to rate coating adhesion from 0B to 5B.

Recorded 5B on flat panels and 4B near edges; Adhesion dropped to 2B after oily handling; Implemented gloves to maintain 5B results.

Temperature Profile

A recorded curve of part (metal) and/or air temperature versus time through the oven, used to verify the cure window is achieved.

Data-logged metal temperature through the oven; Ensured time-above-180°C met cure spec; Identified cold spots causing undercure on large parts.

TGIC Polyester

A widely used exterior-grade powder chemistry where polyester resin crosslinks with TGIC, offering good weatherability and mechanical properties.

Specified TGIC polyester for exterior durability; Considered HAA (TGIC-free) for regulatory reasons; Selected low-gloss TGIC for architectural trim.

Thermoset vs Thermoplastic

Thermoset powders crosslink irreversibly during cure (e.g., epoxy, polyester), while thermoplastics (e.g., nylon, PVC) melt and can be remelted.

Chose thermoset polyester for automotive trim; Used thermoplastic nylon for abrasion resistance; Noted that thermosets don’t remelt upon reheating.

Titration (Bath Control)

Analytical method to measure and control chemical concentrations in pretreatment baths (cleaners, phosphates, seals).

Checked free and total acid in the cleaner daily; Adjusted accelerator after titration drifted; Standardized titration methods across shifts.

Transfer Efficiency

The percentage of sprayed coating that deposits on the part; affected by gun settings, grounding, part geometry, and operator technique.

Improved from 45% to 60% by fixing grounding; Lowered kV to boost penetration in recesses; Balanced powder flow rate to reduce overspray.

Urethane (Polyester-Urethane)

A polyester powder system crosslinked with blocked isocyanates, known for excellent exterior durability, gloss retention, and chemical resistance.

Selected polyester-urethane for superior gloss retention; Used for outdoor furniture due to chemical resistance; Chose urethane for improved hardness.

UV-Curable Powder Coating

Powder technology that melts with IR/heat and then cures via ultraviolet radiation, enabling coating of heat-sensitive substrates at lower temperatures.

Coated MDF with IR melt and UV cure; Reduced part temperature by switching to UV powder; Achieved fast line speeds with UV-cure on plastics.

VOC (Volatile Organic Compounds)

Organic solvents that evaporate during application and curing; powder coatings are typically very low-VOC compared to liquid paints.

Selected low-VOC liquid for touch-up; Powder helped the plant meet VOC permit limits; Tracked VOC emissions for regulatory reporting.

Wash Stages

The number and sequence of steps in a pretreatment washer (e.g., clean, rinse, conversion, rinse, seal), commonly 3-, 5-, or 7-stage systems.

Moved from 3-stage to 7-stage for aluminum; Added a final DI rinse to reduce spots; Balanced stage times to improve throughput.

WIP (Work in Process)

Partially completed items moving through the coating process; controlling WIP reduces lead time, damage risk, and space usage.

Lowered WIP by implementing JIT scheduling; Visual controls prevented mixing of color lots; Tracked WIP days to shorten lead time.

Zinc Phosphate

A heavy-duty crystalline conversion coating that enhances corrosion protection and paint adhesion, widely used in automotive and industrial applications.

Adopted zinc phosphate for higher corrosion class; Verified phosphate weight was within spec; Improved edge protection with zinc phosphate plus primer.

Zinc-Rich Primer

A primer containing high metallic zinc content to provide sacrificial cathodic protection of steel, often used in duplex systems.

Used epoxy zinc-rich primer under polyester topcoat; Met 1,000-hour salt-spray with zinc primer; Specified zinc-rich for coastal installations.