AMPP CAS-2 cheat sheet

Wet film thickness (WFT) = Dry film thickness (DFT) ÷ Volume solids fraction (VS). Example: 4 mils DFT at 50% VS requires 8 mils WFT.

Theoretical coverage (ft²/gal) = 1604 × VS ÷ DFT (mils). Example: 60% VS at 5 mils DFT gives 192 ft²/gal.

Practical coverage accounts for loss factor: Practical coverage = Theoretical coverage × (1 – loss fraction).

Pot life is the maximum time a mixed plural-component coating remains usable; exceeding it causes viscosity rise, gelation, and poor flow-out.

Induction (sweat-in) time is the required waiting period after mixing before application, allowing chemical reaction to initiate.

Stripe coating applies a brush or roller coat to edges, welds, corners, and fasteners before full spray application to ensure adequate DFT at these areas.

Recommended spray gun distance is typically 12–18 inches (30–45 cm) and should be held perpendicular to the surface to minimize overspray and uneven film build.

Environmental application limits: typically surface temperature ≥ 5°F (3°C) above dew point and ≤ 90% RH unless product data sheet states otherwise.

NACE/SSPC abrasive blast cleaning standards: SSPC-SP 5/NACE No. 1 (White Metal), SP 10/NACE No. 2 (Near-White), SP 6/NACE No. 3 (Commercial), SP 7/NACE No. 4 (Brush-Off).

SSPC-SP 1 covers solvent cleaning; SSPC-SP 2 covers hand tool cleaning; SSPC-SP 3 covers power tool cleaning; SSPC-SP 11 covers power tool cleaning to bare metal.

Abrasive blast profile depth is measured per ASTM D4417; typical angular profile for high-performance coatings is 1.5–4 mils (38–100 µm).

Dew point is the temperature at which air becomes saturated; surface temperature must be at least 5°F (3°C) above dew point to prevent condensation.

Relative humidity above 85% (or product-specified limit) can retard abrasive blast cleaning and promote flash rust.

Salt contamination is measured by conductivity per ISO 8502-6/9 (Bresle method); typical acceptance limit for immersion service is ≤ 3 µS/cm or per project specification.

Abrasive cleanliness per SSPC-AB 1 (mineral) or AB 2 (slag) or AB 3 (metallic); contaminants such as oil or salt in abrasive can cause coating failure.

Anchor profile must be appropriate for coating thickness: too shallow causes poor adhesion; too deep can cause thin spots and rust bleed-through.

Dry film thickness (DFT) is measured with a magnetic or eddy-current gauge per SSPC-PA 2; each gauge reading is the average of three spot measurements within a 4-inch (10 cm) diameter area.

SSPC-PA 2 acceptance: average DFT must be ≥ specification; no single spot reading may be < 80% of specification; maximum DFT is typically not limited unless specified.

Wet film thickness is measured with a comb gauge or wheel gauge immediately after application; WFT = DFT ÷ volume solids fraction.

Adhesion testing: ASTM D3359 (tape) for films < 5 mils; ASTM D4541 (pull-off) for thicker films; ASTM D6677 (knife) for evaluation.

Holiday (pinhole) detection: low-voltage wet sponge for films < 20 mils; high-voltage spark tester for thicker or immersion coatings, with voltage set per NACE SP0188 or manufacturer.

Environmental monitoring during application and cure includes ambient temperature, surface temperature, dew point, and relative humidity, recorded at regular intervals.

Visual inspection per SSPC-VIS 1 or ISO 8501-1 compares surface cleanliness to photographic standards before coating application.

Cure evaluation may include solvent rub (ASTM D5402), hardness (ASTM D3363 pencil), or adhesion testing after full cure, per product data sheet.

OSHA permissible exposure limits (PELs) for common solvents: toluene 200 ppm, xylene 100 ppm, MEK 200 ppm, and silica 0.05 mg/m³ (respirable quartz).

Abrasive blasting requires NIOSH-approved supplied-air respirators (Type CE) per OSHA 29 CFR 1910.94 and 1910.134.

Confined space entry requires atmospheric testing for oxygen (19.5–23.5%), flammability (<10% LEL), and toxicity before entry and continuously during work.

VOC content is regulated under EPA 40 CFR Part 59 (National Volatile Organic Compound Emission Standards) and local air district rules; compliant coatings must meet regional VOC limits.

Hazard Communication (OSHA 29 CFR 1910.1200) requires Safety Data Sheets (SDS) and labeling for all hazardous chemicals on site.

Spent abrasive and coating waste may be regulated as hazardous waste under RCRA (40 CFR 261); determine waste classification before disposal.

Fire prevention: store flammable coatings in approved flammable storage cabinets; bond and ground containers during transfer to prevent static ignition.

Hearing protection is required when noise levels exceed 85 dBA (OSHA 29 CFR 1910.95); blasting operations typically exceed this threshold.