AMPP PCS cheat sheet

Barrier, inhibitive, and sacrificial are the three primary protection mechanisms; zinc-rich primers protect by galvanic action, while epoxies typically protect by barrier effect.

Dry film thickness (DFT) is measured on the cured film; wet film thickness (WFT) relates to DFT by WFT = DFT / volume solids fraction.

Volume solids is the fraction of a coating that remains after solvent evaporates; it drives coverage, VOC, and required WFT to reach a target DFT.

Coverage in square feet per gallon at 1 mil DFT = 1604 x (volume solids fraction); divide by target DFT in mils for actual coverage.

Critical pigment volume concentration (CPVC) is the pigment level above which binder no longer fully encapsulates particles; exceeding CPVC causes porosity, blistering, and loss of barrier protection.

Surface preparation standard for a given coating is set by the coating manufacturer; abrasive blast profiles typically fall in the 1.5 to 4 mil range depending on coating type.

Ambient cure conditions: substrate temperature must be at least 5 degrees F (3 degrees C) above dew point, and relative humidity and temperature must fall within the product data sheet range.

Epoxy coatings chalk and lose gloss under UV exposure; aliphatic polyurethanes or polysiloxanes are specified for exterior color and gloss retention.

Pot life is the usable time after mixing a multi-component coating; exceeding pot life degrades adhesion and cure and requires discarding the mixed material.

Inspection holds are points where work cannot proceed without inspector sign-off: typically pre-surface-prep, post-surface-prep, primer application, and final DFT/continuity.

SSPC-SP 10 / NACE No. 2 (near-white blast) permits staining on no more than 5 percent of each unit area; SSPC-SP 5 / NACE No. 1 (white metal) permits no visible residue.

Blast profile is measured by replica tape (press-o-film) or by comparator; surface cleanliness by solvent rub, soluble salt test (Bresle or sleeve), or visual comparator.

Soluble salt contamination is measured in conductivity units; common acceptance limits are on the order of 3 to 5 microsiemens/cm depending on the specification.

DFT on steel is measured with magnetic pull-off or magnetic induction gauges; on non-ferrous substrates an eddy-current gauge is used.

A Type 1 or Type 2 DFT gauge requires calibration verification against foils or a known standard before and after each inspection series.

Holiday/continuity testing: low-voltage wet-sponge for thin films, high-voltage spark tester for thick films; voltage must be set per the specification and film thickness.

Adhesion is verified by pull-off (ASTM D4541) or cross-cut/knife tests; cohesive failure within the coating differs from adhesive failure at the substrate interface.

Environmental readings (ambient and substrate temperature, dew point, RH) are recorded before, during, and after application to document compliance with the product data sheet.