Field math, done for you.

Theoretical math. Profile, texture, wind, edges and gun technique change real-world yield — log your actual numbers and adjust the waste factor.

A-side

The isocyanate component. In aromatic polyurea it is usually an MDI-based prepolymer. Moisture-sensitive — keep it sealed and dry.

Adhesion (pull-off) test

Gluing a dolly to the cured coating and pulling it off with a calibrated tester (ASTM D4541 for metal, D7234 for concrete) to measure bond strength.

Aliphatic

Isocyanate chemistry that holds its color and gloss in sunlight. Costs more; usually used as a topcoat.

Amine

The reactive groups on the B-side resins and chain extenders that react with isocyanate to form urea.

Aromatic

MDI-based chemistry. Strong and economical, but it darkens and chalks in UV.

B-side

The resin component — amine-terminated resins plus chain extenders, pigments and additives. Pure polyurea uses amines only; hybrids add polyols.

Blister

A raised bubble under or in the film, often from moisture or outgassing from the substrate.

Chain extender

A small diamine molecule in the B-side that controls hardness and reaction speed.

CSP

Concrete Surface Profile, ICRI’s 1–10 scale (Guideline 310.2R) describing how rough prepared concrete is.

Delamination

Loss of bond between the coating and the substrate, or between coats. Almost always a prep, moisture or recoat-window issue.

Desiccant dryer

A cartridge on the drum vent that dries incoming air so the isocyanate doesn’t react with humidity and crystallize.

Dew point

The temperature at which moisture condenses out of the air. Surfaces near or below it are wet even when they look dry.

DFT

Dry film thickness — how thick the cured coating is, usually in mils.

Dynamic pressure

Pressure while the gun is spraying. Compare A and B — a big gap points to a restriction or feed problem.

Elongation

How far the coating stretches before breaking, as a percent (ASTM D412). High elongation = crack bridging.

Gel time

Seconds from mixing until the material stops flowing. Spray polyurea gels in seconds.

Heated hose

An insulated hose bundle with a heating element that keeps both sides at temperature all the way to the gun.

Hybrid polyurea

A system whose B-side blends amines with polyols, making a polyurea/polyurethane film. Cheaper and forgiving; different performance than pure.

Impingement mixing

High-pressure streams of A and B colliding in the gun’s mix chamber. It’s how fast-set materials mix without a static mixer.

Isocyanate

The reactive chemistry of the A-side (NCO groups). A respiratory and skin sensitizer — the reason for supplied air and full PPE when spraying.

Mil

One thousandth of an inch (0.001 in = 25.4 µm). A credit card is about 30 mils.

Mix chamber

The small part inside the gun where A and B meet. Its size sets output and pattern.

MVER

Moisture vapor emission rate from concrete, measured with the calcium chloride test (ASTM F1869), in lb/1,000 sq ft/24 h.

Off-ratio

A:B mixing that strays from the specified ratio. Too much B tends to be soft and sticky; too much A can be brittle.

Outgassing

Air and vapor escaping a porous substrate as it warms, causing pinholes and bubbles. Prime, and spray when the slab is cooling.

Pinholes

Tiny holes through the film, usually from outgassing or a contaminated surface.

Plural-component

Any system where two (or more) components are metered and mixed at the gun rather than in a pail.

Polyaspartic

An aliphatic polyurea made with polyaspartic ester amines, so it cures in minutes instead of seconds and can be rolled.

Polyurethane

Coatings formed from isocyanates reacting with polyols (alcohols). Slower and more moisture-sensitive than polyurea.

Primer

A first coat that seals and bonds to the substrate — critical on concrete to stop outgassing and improve adhesion.

Proportioner

The machine (often called a reactor) that heats both components and pumps them at a fixed ratio and pressure.

Purge

How the gun clears mixed material from its chamber: with air (air-purge) or a rod (mechanical purge).

Ratio check

Spraying A and B separately into containers to verify the machine is delivering the right ratio.

Recoat window

How long you have to apply the next coat so it bonds chemically without sanding or priming.

Relative humidity

Moisture in the air as a percent of the maximum it could hold at that temperature.

Secondary containment

A lined area around tanks that holds spills and leaks. In the U.S., oil storage falls under EPA SPCC rules (40 CFR 112).

Shore hardness

Durometer reading (ASTM D2240). Shore A for rubbery films, Shore D for harder ones.

Side seals

Seals on each side of the mix chamber that keep A and B separated until mixing. A common wear part.

Static pressure

Pressure with the gun trigger released. Should be stable and roughly balanced between A and B.

Substrate

Whatever you’re coating — concrete, steel, wood, foam, existing coatings.

Tack-free time

When the surface stops feeling sticky to a light touch.

Tear strength

Resistance to a tear propagating once started (ASTM D624), in pounds per linear inch (pli).

Tensile strength

Force needed to pull the film apart (ASTM D412), in psi.

Topcoat

A final coat — often aliphatic polyurea or polyaspartic — for UV stability, color, gloss or chemical resistance.

Transfer pump

The pump that feeds material from drums to the proportioner.

Volume solids

The share of a coating that remains as film after curing. Most spray polyurea is close to 100%.

No terms match. Ask the forum — someone knows.