AMPP S-CAT key terms

A surface preparation method that propels abrasive particles at high velocity against a substrate to remove rust, mill scale, old coatings, and other contamination, creating a roughened profile that promotes coating adhesion.

Any natural or manufactured particulate material, such as garnet, aluminum oxide, or slag, used in blast cleaning to cut and clean a surface. Hardness, size, and shape determine its cutting effectiveness and the resulting profile.

The microscopic roughness pattern produced on a substrate by blast cleaning or other mechanical preparation. Adequate profile gives the coating a mechanical key for adhesion and is measured in mils or micrometers.

The network of peaks and valleys on a prepared surface that the coating mechanically grips. Depth and density of the anchor pattern influence adhesion and how much coating is needed to cover the peaks.

A standardized description of how thoroughly a surface has been cleaned, such as white metal, near-white, or commercial blast. The grade defines how much visible contamination, staining, or residue may remain before coating.

Removal of oil, grease, dirt, and similar soluble contamination using solvents, detergents, or emulsion cleaners before mechanical preparation. Doing it first prevents contaminants from being driven into the surface during blasting.

Surface preparation using non-power tools such as wire brushes, scrapers, and sandpaper to remove loose rust, scale, and old paint. It is limited to light-duty service and does not create a meaningful anchor pattern.

Preparation using powered equipment such as grinders, sanders, and needle guns to remove rust, scale, and coatings. It achieves better cleaning than hand tools but typically produces a shallower profile than abrasive blasting.

A blast cleaning method in which water is introduced into the abrasive stream to suppress dust and, in some configurations, to wash soluble salts from the surface during cleaning.

Chlorides, sulfates, and similar ionic compounds left on a surface by seawater, chemicals, or perspiration. If not removed before coating, they draw moisture and cause premature blistering and undercutting.

The air pressure measured at the blast nozzle while blasting. It largely controls cleaning speed and profile depth; low pressure at the nozzle means the surface may not reach the specified cleanliness or roughness.

A durable metallic or mineral blast media designed to be recovered, cleaned, and reused multiple times. Reuse reduces waste and cost but requires monitoring for breakdown and contamination.

The handheld device in a spray coating system that atomizes coating and directs it toward the substrate. Its fluid tip, needle, and air cap control the spray pattern, flow rate, and degree of atomization.

The process of breaking liquid coating into fine droplets so it can be carried to the surface in a uniform spray. Poor atomization causes orange peel, spitting, or uneven film thickness.

The replaceable nozzle orifice in a spray gun that meters coating flow. Tip size must suit the coating's viscosity and the desired film build; too small a tip starves the pattern, too large a tip floods it.

The component at the front of a spray gun that shapes and atomizes the spray using compressed air. Its horn holes and center port determine pattern width, atomization quality, and how much air is consumed.

A spray method that forces coating through a small orifice at high hydraulic pressure, atomizing it without compressed air. It handles high-viscosity materials and high film builds but produces a coarser pattern.

A spray method in which compressed air atomizes the coating at the gun. It gives fine atomization and good finish quality but is less efficient and less suited to high-viscosity or high-build coatings.

Enlargement of a spray tip orifice from abrasive coating passage over time. Worn tips increase flow and distort the pattern, causing excess film thickness and uneven coverage until the tip is replaced.

The shape and width of the fan of coating leaving the gun, controlled by the air cap, tip, and gun distance. A consistent, evenly tapered pattern is needed for uniform overlap and film thickness.

The amount by which each spray pass covers the previous pass, typically about half the pattern width. Correct overlap prevents thin stripes and skips; too little overlap leaves holidays in the film.

The thickness of coating measured immediately after application while still wet. It is checked with a comb gauge and used to predict dry film thickness so application can be corrected before the coating cures.

The thickness of the cured coating measured on the finished surface, usually with a magnetic or eddy-current gauge. It is the acceptance criterion for most coating specifications and must fall within the specified range.

A unit of coating thickness equal to one thousandth of an inch, commonly used in coating specifications. Metric equivalents are expressed in micrometers, where one mil equals about 25.4 micrometers.

A gap, pinhole, or thin spot in a coating that leaves the substrate insufficiently protected. Holidays are located with a high-voltage or wet-sponge detector and must be repaired before the coating is accepted.

A tiny hole through a coating film, often caused by trapped solvent, air, or surface contamination. Pinholes breach the barrier and can lead to localized corrosion if not detected and repaired.

A surface defect with a bumpy, citrus-like texture caused by poor atomization, incorrect viscosity, too much air, or improper gun distance. It is largely cosmetic but can affect appearance and coverage.

A measure of a coating's resistance to flow. It determines whether the material can be atomized and applied properly; it is adjusted with thinners and checked against the manufacturer's recommended range.

A solvent added to a coating to reduce viscosity for spraying or brushing. The correct type and amount are specified by the manufacturer; over-thinning can cause sagging, low film build, and poor performance.

The working time after a multi-component coating is mixed during which it remains usable. Once exceeded, the material thickens or gels and must be discarded rather than thinned or sprayed.

The lowest temperature at which a liquid gives off enough vapor to ignite briefly when exposed to an ignition source. It is a key hazard indicator for solvents and determines safe storage and ventilation requirements.

The controlled movement of air to remove solvent vapors, dust, and overspray from a work area. Adequate ventilation keeps airborne concentrations below exposure limits and reduces fire and health hazards.

Personal protective equipment worn over the face to filter airborne particles or vapors. Selection depends on the hazard, and proper fit testing and cartridge change schedules are required for effective protection.

Clothing, eye protection, gloves, and respiratory protection worn to shield the worker from coatings, solvents, abrasives, and noise. It is the last line of defense after engineering and administrative controls.

An enclosed area with limited entry and exit that is not designed for continuous occupancy, such as a tank interior. Entry requires atmospheric testing, permitting, and an attendant outside the space.

A type of air compressor that uses pistons to compress air and can introduce oil carryover into the air supply. Oil-contaminated air causes coating defects, so filtration and traps are required.