1. Classify the Environment First
Start with ISO 12944-2. Map the structure to a corrosivity category (C2–C5, Im1–Im3, or CX for offshore/extreme) and decide the required durability (low / medium / high / very high). Picking the category before comparing products prevents over- or under-specifying the system.
For bridges and port structures, C4–C5-M is common; immersion zones (pilings, ballast tanks) fall under Im1–Im3 and need different primers and DFT budgets.
2. Build the Coating System, Not a Single Product
Durability comes from the stack: a zinc-rich primer for cathodic protection, a micaceous iron oxide (MIO) intermediate for barrier thickness, and a polyurethane or fluorocarbon topcoat for UV and weathering.
Always verify inter-coat compatibility and the recommended overcoating window. A mismatch between primer and finish is a frequent, avoidable failure.
3. Specify Measurable Acceptance Criteria
Write the spec in numbers: dry film thickness (DFT) range, pull-off adhesion (ISO 4624), holiday/porosity test, and salt-spray or cyclic-corrosion hours. Vague clauses like 'apply two coats' cannot be inspected.
4. Verify On Site
Confirm blast cleanliness (Sa 2.5), ambient conditions (surface temp at least 3°C above dew point, RH < 85%), and wet-film thickness during application. Document each shift so failures are traceable.
Need the full TDS/SDS or a custom formulation consultation? Contact our technical team.