When you start talking to epoxy contractors, you are going to hear a lot of terminology. Some of it is straightforward; some of it is genuinely technical. This glossary gives you a plain-language definition for the 50 terms you are most likely to encounter — so you can follow the conversation, ask better questions, and know whether what you are hearing makes sense.
- 100% Solids Epoxy
- An epoxy formulation that contains no water or solvents. When it cures, essentially all of the material remains in the coating. This produces a thicker, harder, more durable film than water-based or solvent-based alternatives. It is the professional standard for most garage and commercial applications.
- Acid Etching
- A surface preparation method that uses diluted muriatic (hydrochloric) acid to chemically open the pores of concrete and remove surface laitance. Less effective than mechanical prep methods. More common in DIY applications. Not recommended as the sole prep method for professional installations.
- Adhesion
- The bond between the epoxy coating and the concrete substrate, or between individual coats in a multi-layer system. Adhesion failure is the root cause of peeling and delamination.
- Aggregate
- Textured particles (sand, quartz, aluminum oxide) added to coatings to increase slip resistance and durability. Often broadcast into a wet base coat or incorporated into a topcoat formula.
- Amine Blush
- A waxy or oily film that can form on the surface of an amine-cured epoxy when it is applied in high humidity or low temperature conditions. It looks cloudy or hazy and interferes with adhesion of subsequent coats. Can be removed with a light scrub and rinse.
- Base Coat
- The primary epoxy layer that provides the color, body, and core performance of the flooring system. Applied over the primer and under any broadcast material and topcoat.
- Broadcast
- The process of scattering decorative flakes, colored chips, or aggregate into a wet base coat while it is still tacky. Creates a textured, decorated surface that is then sealed with a topcoat.
- Calcium Chloride Test (ASTM F1869)
- A moisture test that measures moisture vapor emission rate (MVER) from a concrete slab. Calcium chloride crystals are placed under a sealed dome on the concrete surface for 60 to 72 hours. The weight gain of the crystals indicates how much moisture is moving through the slab.
- Chemical Resistance
- The ability of a cured epoxy coating to withstand exposure to acids, bases, solvents, fuels, and other chemicals without degrading or discoloring. Different epoxy formulations offer different levels of chemical resistance.
- Clear Coat
- See Topcoat. A clear protective layer applied over the decorative system.
- Color Flakes / Vinyl Chips
- Small colored vinyl or acrylic flakes broadcast into a wet base coat to create a decorative, speckled appearance and a lightly textured surface. Also called "chip flakes" or "paint chips."
- Compressive Strength
- The load-bearing capacity of cured concrete, typically measured in PSI (pounds per square inch). Most epoxy systems require a minimum concrete compressive strength to adhere properly. Standard for residential floors is 3,000 PSI or greater.
- Concrete Laitance
- A weak, powdery layer of cement dust, fine aggregates, and calcium carbonate that forms on the surface of concrete as it cures. It prevents proper epoxy adhesion and must be removed during surface preparation.
- Coverage Rate
- The area a unit volume of coating (typically one gallon) will cover at the specified thickness. Coverage rates are specified in square feet per gallon on the product's technical data sheet.
- CSP (Concrete Surface Profile)
- A standardized scale (CSP 1 through CSP 10) developed by the International Concrete Repair Institute (ICRI) that describes the texture and roughness of a concrete surface. Epoxy coatings typically require CSP 2 to CSP 4. Shot blasting and diamond grinding achieve this profile.
- Cure Time
- The time required for the coating to reach its full hardness, chemical resistance, and performance properties after application. Different from dry time. Full chemical cure for most epoxy systems is 28 days, though the floor is usable well before that.
- Delamination
- The separation of the epoxy coating from the concrete substrate or from a previous coat. The technical term for peeling.
- Diamond Grinding
- A mechanical surface preparation method using a walk-behind grinder equipped with diamond-segment discs. Removes surface contaminants and profiles the concrete. Effective and flexible; used on most professional installation jobs.
- Dry Film Thickness (DFT)
- The thickness of the cured coating, measured in mils (thousandths of an inch). DFT determines durability and performance. Professional epoxy systems are typically 10 to 20 DFT. Consumer kits are often 3 to 5 DFT.
- Dry Time
- The time required before the next coat can be applied, or before foot traffic is allowed. Not the same as cure time. A coating can be dry to the touch but not fully cured.
- Epoxy
- A thermosetting polymer formed by the reaction of a resin (Part A) with a hardener or curing agent (Part B). In flooring, "epoxy" refers to both the product and the installed coating system.
- Epoxy Mortar
- A very thick epoxy mixture containing high-ratio aggregate (usually sand). Used to fill large cracks, holes, and damaged areas in concrete before a topcoat system is applied. Also used as a stand-alone flooring system in extreme industrial environments.
- Flake System
- A multi-layer epoxy flooring system that includes a broadcast of vinyl color flakes into the base coat, followed by a sealing topcoat. One of the most popular residential and light commercial systems due to its appearance and the ability of the flakes to hide minor surface imperfections.
- Hardener
- The Part B of a two-part epoxy system. The hardener (typically amine-based) initiates and drives the chemical curing reaction when mixed with the resin. The ratio of resin to hardener is critical and must match the manufacturer's specification.
- Holiday
- An area of missed coverage in a coating application. A holiday can appear as a thin spot, a visible void, or an area of different sheen. Found during inspection by raking a bright light at a low angle across the surface.
- Hot Tire Pickup
- A failure mode specific to garage floors where a vehicle tire, heated during driving, bonds to the epoxy surface and pulls off a section of coating when the vehicle moves. Associated with epoxy base coats that do not have a polyaspartic or polyurethane topcoat with sufficient hardness.
- Hydrostatic Pressure
- Pressure exerted by groundwater pushing up against and through a concrete slab from below. Extreme hydrostatic pressure can cause coating delamination even in systems with moisture-mitigating primers.
- Intercoat Adhesion
- The bond between successive coats in a multi-layer system. Can fail if the previous coat has fully cured past its recoat window without mechanical scuffing between layers.
- Laitance
- See Concrete Laitance.
- Metallic Epoxy
- A specialty epoxy system that uses metallic pigments suspended in the coating to create a three-dimensional, liquid-metal appearance. Requires skilled application technique and is typically more expensive than flake systems.
- Mil
- A unit of measurement equal to one-thousandth of an inch (0.001 inch). Used to measure coating thickness. 10 mils equals approximately 0.010 inches. Professional epoxy systems are typically 10 to 20 mils total film thickness.
- Mix Ratio
- The ratio by volume or weight at which the two components (resin and hardener) of an epoxy system must be combined. Getting the mix ratio wrong produces a coating that will not cure correctly.
- Moisture Vapor Emission Rate (MVER)
- The rate at which moisture vapor moves through a concrete slab, expressed in pounds of water per 1,000 square feet per 24 hours. Measured by the calcium chloride test. Most epoxy systems require MVER below 3 lbs/1,000 sf/24 hrs for standard application; moisture-tolerant primers handle higher rates.
- Outgassing
- The release of air or gas bubbles from concrete during epoxy application. Occurs when the concrete is warm and the pores release air as the epoxy is applied. Results in pinholes or pocking on the surface. Managed by applying epoxy during cooler parts of the day or using a penetrating primer.
- Polyaspartic
- A type of polyurea coating used primarily as a fast-curing, UV-stable topcoat in epoxy flooring systems. Extremely hard, excellent chemical resistance, cures in 1 to 4 hours. Often used in one-day installation systems.
- Polyurea
- A fast-reacting, highly flexible coating derived from isocyanates and amines. Sometimes used as a base coat or topcoat in flooring systems. Extremely durable and flexible but requires specialized application equipment.
- Polyurethane
- A topcoat option for epoxy floors that offers good chemical resistance, hardness, and moderate UV stability. A step below polyaspartic in both UV resistance and cure speed but widely used and effective.
- Primer
- The first coat applied to prepared concrete. Penetrates into the surface and creates a foundation for the epoxy system. In moisture-prone environments, a moisture-mitigating primer is used to reduce vapor transmission before the decorative coats are applied.
- Pot Life
- The working time available after the resin and hardener are mixed before the material becomes too thick to apply. Ranges from minutes (polyaspartic) to hours (standard epoxy). High temperatures shorten pot life.
- Recoat Window
- The time range within which the next coat must be applied over the previous one to achieve proper intercoat adhesion without mechanical scuffing. Apply too soon and you risk trapping solvents; apply too late and you must scuff or abrade the surface.
- Relative Humidity (RH) Test (ASTM F2170)
- An in-slab moisture test that measures the relative humidity inside a drilled hole in the concrete slab. Considered more accurate than surface-only tests like calcium chloride. Most epoxy systems specify a maximum in-slab RH of 75 to 85 percent.
- Resin
- The Part A of a two-part epoxy system. Typically a bisphenol A or F epoxide. Does not cure on its own; must be combined with the hardener in the specified ratio.
- Self-Leveling Epoxy
- A low-viscosity epoxy that flows and settles under its own weight to create a smooth, level surface. Requires a perimeter barrier and careful substrate leveling before application.
- Shot Blasting
- A mechanical surface preparation method using a self-contained machine that propels steel shot at the floor surface at high velocity, then recovers it. Creates an aggressive surface profile and removes most contaminants simultaneously. The preferred prep method for professional epoxy installations.
- Slip Resistance
- A measure of the traction offered by a floor surface, typically expressed as a coefficient of friction (COF). Smooth epoxy surfaces can be slippery when wet. Anti-slip additives (aluminum oxide, quartz) or textured broadcast systems increase slip resistance.
- Solids Content
- The percentage by volume of a coating that remains as film after the volatile components (water or solvents) evaporate. 100% solids means no volatiles. Water-based epoxies may have 40 to 50% solids content, meaning up to half the volume evaporates and the dry film is thinner than the wet film.
- Substrate
- The surface to which the coating is applied. In epoxy flooring, the substrate is almost always concrete.
- Surface Profile
- The texture of a prepared concrete surface. Measured on the CSP scale. Adequate surface profile is required for mechanical adhesion of the epoxy coating.
- Topcoat
- The final, outermost layer of the flooring system. Provides chemical and abrasion resistance, sets the gloss level, and protects the decorative layers beneath. Common topcoat materials include polyaspartic, polyurethane, and epoxy clear.
- VOC (Volatile Organic Compound)
- Carbon-containing chemicals that evaporate at room temperature and contribute to air quality concerns and odor. Regulated by EPA and some state agencies. Water-based epoxies have the lowest VOC levels; solvent-based systems have the highest.
- Workmanship Warranty
- A contractor's guarantee that the installation was performed correctly and that defects resulting from installation errors will be repaired at no cost within the warranty period.