AMPP CAS-1 cheat sheet

Wet film thickness (WFT) relates to dry film thickness (DFT) by DFT = WFT × percent volume solids (fraction), ignoring loss; use the fraction, not the percent number.

Practical coverage in ft²/gal = 1604 × (% volume solids ÷ 100) ÷ DFT in mils; at 100% solids and 10 mils DFT, coverage is about 160 ft²/gal.

For a multi-coat system, total DFT equals the sum of individual coat DFTs; a stripe coat adds material at edges and welds and is counted separately.

Theoretical spreading rate (ft²/gal) = 1604 ÷ (DFT in mils) for 100% solids; higher volume solids at equal DFT gives greater coverage.

Airless spray pressure typically ranges around 1,500-3,000 psi and is adjusted to atomize without excessive overspray; tip orifice and fan angle are chosen for the target WFT.

Conventional air spray delivers lower viscosity material at lower pressure and produces more overspray and solvent emission than airless for high-solids coatings.

Recoat window is the interval during which the next coat may be applied without surface preparation; exceeding it usually requires abrasion or solvent wipe per the product data sheet.

Induction time is the required standing period between mixing components and application for some plural-component or catalyzed products; it is specified on the product data sheet.

Ambient and substrate temperature, relative humidity, and dew point govern cure; most generic specifications prohibit application when substrate temperature is within 5°F (3°C) of the dew point.

Abrasive blast cleanliness grades per SSPC-SP: SP 5 (white metal), SP 10 (near-white), SP 6 (commercial), SP 7 (brush-off); SP 5 and SP 10 are the most common for immersion service.

Blast profile is measured by comparator or surface profile gauge; typical angular profile for many high-performance systems is about 1.5-4 mils depending on coating and specification.

SSPC-SP 1 covers solvent cleaning to remove oil, grease, and dirt before mechanical preparation; contaminants must be removed before blasting to avoid driving them into the surface.

SSPC-SP 2 (hand tool) and SP 3 (power tool) cleaning remove loose material but leave tightly adherent mill scale and rust; they are not equivalent to abrasive blasting.

SSPC-SP 11 covers power-tool cleaning to bare metal; SSPC-SP 15 covers commercial-grade power-tool cleaning.

Waterjetting grades per SSPC-SP 12 (WJ-1 through WJ-4) describe cleanliness; flash rust grades (L, M, H) describe rust severity after waterjetting.

Abrasive must be clean, dry, and free of oil or salt contamination; recycled abrasive can carry chlorides and fines that degrade the profile and adhesion.

Anchor profile should be appropriate to coating thickness: profile too coarse for a thin film can cause pinholes, while too fine a profile reduces mechanical adhesion.

Soluble salt contamination (chlorides, sulfates) is measured by conductivity or specific ion test kits; residual salts above specification limits cause premature coating failure.

DFT is measured with magnetic or eddy-current gauges; a common rule is to take a minimum of three readings per 100 ft² (or per specified area) and average them, with no single reading below the specified minimum.

Type 1 gauges use magnetic pull-off; Type 2 gauges are electronic. Eddy-current gauges measure nonconductive coatings on nonferrous substrates.

Holiday (spark) testing uses high-voltage or low-voltage detectors; voltage is set per coating thickness and product data sheet to detect pinholes and thin spots.

Adhesion testing methods include pull-off (ASTM D4541) and knife/scribe tests; pull-off reports tensile strength in psi and the failure mode (cohesive vs. adhesive).

Wet film thickness is measured with a comb or wheel gauge; DFT = WFT × volume solids fraction, so WFT can be used to verify compliance during application.

Environmental readings recorded during inspection include air temperature, substrate temperature, relative humidity, dew point, and the dew point spread (substrate temperature minus dew point).

A hold point is a step that cannot proceed without inspector approval; a witness point requires notification but not necessarily approval before proceeding.

Cure verification may use solvent rub, hardness, or cure-test methods; premature topcoating over an undercured coat can cause wrinkling or solvent entrapment.

Instrument calibration and verification should be documented before use; gauge readings on curved or edge surfaces are unreliable and should be avoided or corrected.

The dew point spread is substrate temperature minus dew point; a spread of at least about 5°F (3°C) is commonly required before application to avoid condensation on the surface.

VOC content of a coating is the mass of volatile organic compounds per unit volume; low-VOC and waterborne products reduce emissions and may require different application equipment.

Abrasive blasting generates silica dust; use of silica-containing abrasives requires respiratory protection and dust controls per applicable occupational exposure limits.

Confined space entry requires atmospheric testing for oxygen, flammables, and toxics, plus a permit, attendant, and rescue plan before entry.

Solvents and coatings must be stored and handled per SDS requirements; flammable liquids require bonding and grounding during transfer to prevent static ignition.

Spent abrasive, paint waste, and solvent rags are regulated wastes and must be characterized and disposed of per applicable environmental rules; they are not ordinary trash.

Spray application in enclosed areas requires ventilation and respiratory protection; isocyanate-containing products require supplied-air or appropriate cartridge protection per SDS.

Fall protection, scaffolding inspection, and equipment guarding apply to surface preparation and coating work at height or with rotating and high-pressure equipment.