The polyurea industry uses a specific technical vocabulary drawn from polymer chemistry, protective coatings, construction, and industrial hygiene. This glossary defines the key terms encountered in polyurea specifications, technical data sheets, standards documents, and professional discussions. Terms are organized alphabetically within categories for easy reference.
Chemistry & Materials
Amine — The chemical functional group (–NH₂ or –NH–) that forms the reactive component in the polyurea B side. Amines react rapidly with isocyanates to form polyurea linkages without requiring a catalyst. See also: Isocyanate, Polyurea Reaction.
Aromatic Polyurea — A polyurea system in which the isocyanate component contains aromatic (benzene ring) structures. Aromatic systems are generally less expensive and have higher physical properties than aliphatic systems, but yellow and chalk when exposed to UV radiation. Suitable for applications where color stability is not critical. Compare with: Aliphatic Polyurea.
Aliphatic Polyurea — A polyurea system using an aliphatic (non-aromatic) isocyanate. Aliphatic systems maintain color and gloss stability under UV exposure and are specified where appearance is important. Generally more expensive than aromatic equivalents. Common isocyanate: HDI (hexamethylene diisocyanate) and its derivatives.
A Side — The isocyanate component of a two-component polyurea system, typically pure MDI or a prepolymer blend. The A side is highly reactive with moisture and should be kept sealed when not in use. See also: Isocyanate, Prepolymer.
B Side — The amine resin component of a polyurea system. The B side contains the chain extenders, curatives, pigments, and performance additives that determine much of the cured coating’s physical properties. See also: Amine, Chain Extender.
Chain Extender — A short-chain diamine used in the polyurea B side that controls crosslink density, hardness, and flexibility of the cured polymer. Common chain extenders include DETDA (diethyltoluenediamine) and DMTDA.
Elongation — A measure of how much a cured polyurea film can stretch before breaking, expressed as a percentage of the original length. Typical polyurea elongation values range from 200% to 600%. Higher elongation indicates greater flexibility and crack-bridging ability. Measured per ASTM D412. See also: Tensile Strength.
Gel Time — The time from when the A and B components contact each other until the mixed material transitions from liquid to a gel state and can no longer flow. Most commercial polyurea systems have gel times of 3-15 seconds. Not to be confused with Tack-Free Time or Full Cure Time.
Hardness (Shore A and Shore D) — A measure of a material’s resistance to indentation, measured on a scale of 0-100. Shore A is used for softer elastomers; Shore D for harder materials. Most polyurea coatings fall in the Shore A 70-100 range. Measured per ASTM D2240.
Hybrid Polyurea / Polyurea-Polyurethane Hybrid — A coating system that combines amine (polyurea) and polyol (polyurethane) chemistry in the B side. Hybrids offer a wider range of adjustable properties and lower cost than pure polyurea, but may be more moisture-sensitive during application and slower curing than pure polyurea systems.
Isocyanate — The reactive chemical functional group (–N=C=O) and the materials containing it (the polyurea A side). Isocyanates react with amines to form polyurea and with water to form CO₂ (causing foaming if moisture intrudes). The principal isocyanate used in polyurea is MDI (methylene diphenyl diisocyanate).
MDI (Methylene Diphenyl Diisocyanate) — The most common isocyanate used in polyurea systems. Available as pure MDI (4,4′-MDI), modified liquid MDI, and isocyanate prepolymers. The specific MDI form used affects reactivity, application properties, and cured film performance.
Mix Ratio — The volumetric ratio at which the A and B components must be combined for the polyurea system to achieve its specified properties. Most commercial polyurea systems have a 1:1 (equal volume) mix ratio, though some systems use 2:1 or other ratios. Deviation from the specified ratio — even by a few percent — can significantly affect cured film properties.
Prepolymer — An isocyanate pre-reacted with a polyol to reduce vapor pressure and improve handling characteristics. Prepolymer-based polyurea A sides are less volatile and often more flexible than those using pure MDI.
Tensile Strength — The maximum stress a cured polyurea film can withstand before breaking, typically expressed in PSI (pounds per square inch) or MPa. Commercial polyurea tensile strengths range from approximately 1,000 PSI to 5,000+ PSI. Measured per ASTM D412. See also: Elongation.
Application & Equipment
Dry Film Thickness (DFT) — The thickness of the cured polyurea coating measured in mils (thousandths of an inch) or micrometers. Because polyurea is typically 100% solids, DFT equals Wet Film Thickness (WFT) for most systems. See also: Wet Film Thickness, Mil.
Heated Hose — The electrically heated supply lines in a plural component spray system that maintain the A and B components at the specified processing temperature as they travel from the proportioning unit to the spray gun. Heated hose management is critical for maintaining consistent material temperature and viscosity at the gun.
Holiday — A discontinuity (pinhole, skip, thin area) in an applied coating that allows the substrate to be exposed. In wastewater and chemical containment applications, holidays are detected using electrical spark testing (holiday detection). In bridge coatings and secondary containment, holidays must be repaired before the lining system is accepted.
Mil — One thousandth of an inch (0.001″). Coating thickness is commonly specified in mils. 1 mil = 25.4 micrometers. See also: Dry Film Thickness.
Plural Component Sprayer — Equipment that simultaneously meters, heats, and proportions the A and B components and mixes them in the spray gun immediately before application. The primary equipment category for professional polyurea application. Leading manufacturers include Graco, Gusmer, and PMC.
Spray Gun (Impingement Mixing) — The mixing head on a plural component spray system where the A and B streams collide at high pressure and velocity, creating mechanical mixing of the components without a static mixing element. Also called a “proportioning gun” or “impingement mix gun.”
Wet Film Thickness (WFT) — The thickness of the coating immediately after application, before cure. For 100% solids polyurea, WFT equals DFT. For solvent-borne systems, WFT is greater than DFT because solvent evaporates during cure. See also: Dry Film Thickness.
Surface Preparation
Abrasive Blasting — A surface preparation method using compressed air to propel abrasive media at high velocity to clean and profile the substrate surface. See also: Near-White Metal Blast, White Metal Blast.
CSP (Concrete Surface Profile) — A standardized measure of concrete surface texture on a 1-9 scale defined by ICRI Guideline 310.2R. CSP 1 is a near-smooth surface; CSP 9 is extremely rough. Most polyurea applications on concrete specify CSP 3-6. See also: ICRI.
Dew Point — The temperature at which air becomes saturated with moisture and water condenses on surfaces. Critical for coating application: substrate temperature must be at least 5°F above the dew point to prevent moisture condensation on the surface during application.
Diamond Grinding — A surface preparation method using rotating diamond-tipped abrasive tools to grind concrete surfaces. Produces a flat, consistent profile (CSP 2-3). See also: CSP, Shot Blasting, Scarifying.
MIC (Microbiologically Influenced Corrosion) — Corrosion accelerated by the activity of microorganisms, particularly common in wastewater environments where sulfate-reducing bacteria produce hydrogen sulfide that oxidizes to sulfuric acid. Polyurea coatings are used to prevent MIC attack on concrete in wastewater structures.
Near-White Metal Blast (SSPC-SP 10) — A surface cleanliness standard for steel blast cleaning where visible rust, mill scale, paint, and foreign matter have been removed from 95% of each unit area of the surface. The standard specification for most polyurea applications on structural steel.
Shot Blasting — A surface preparation method using centrifugally propelled steel shot to clean and profile concrete or steel surfaces. The preferred method for preparing large horizontal concrete surfaces because the self-contained machine captures spent shot and debris for recycling. See also: Abrasive Blasting, CSP.
White Metal Blast (SSPC-SP 5) — The highest steel surface cleanliness standard, requiring complete removal of all rust, mill scale, and coatings from 100% of the surface. Specified for immersion service and highly corrosive environments. More demanding and expensive than Near-White Metal Blast (SSPC-SP 10).
Testing & Inspection
Adhesion Test (Pull-Off Test) — A method for measuring the bond strength of a coating to its substrate, performed by gluing a test dolly to the coating surface and measuring the force required to pull it off in tension. Measured per ASTM D4541. Results reported in PSI. Used in wastewater, infrastructure, and industrial coating quality control.
Holiday Detection — The process of checking an applied coating for discontinuities (holidays) using an electrical test method. Low-voltage wet sponge testing is used for thin coatings; high-voltage spark testing (jeeping) is used for thick coatings and linings in chemical and water service. See also: Holiday.
Taber Abraser Test (ASTM D4060) — A standardized abrasion resistance test method using rotating abrasive wheels under specified weight. Results reported as weight loss in milligrams per specified number of cycles (typically 1,000). Used to compare abrasion resistance between polyurea formulations and to specify mining-grade systems.
Standards & Certifications
AMPP — Association for Materials Protection and Performance, formed from the 2021 merger of NACE International and SSPC. Manages coating inspection certifications (CIP), contractor qualification programs, and key protective coatings standards. See also: NACE, SSPC.
ICRI — International Concrete Repair Institute. Publishes guidelines for concrete surface preparation, repair, and coating application including the CSP surface profile standards widely referenced in polyurea specifications.
NACE — National Association of Corrosion Engineers (now part of AMPP). See AMPP.
NSF/ANSI 61 — The standard for drinking water system components, including coatings in contact with potable water. Polyurea formulations used in potable water storage tanks, cisterns, and water treatment infrastructure must carry NSF 61 certification.
SSPC — Society for Protective Coatings (now part of AMPP). See AMPP.
For additional technical resources, visit the Industry Resources & Standards page. For practical guidance on using these standards in real projects, explore our Applications section or connect with experienced members through the Community. View our FAQ for answers to common questions about polyurea technology and applications.
