Coating system
Primer, intermediate and topcoat specified together with a total dry film thickness, and qualified as a set. Substituting one layer from another manufacturer without a compatibility check is where a specification quietly stops being one.
The layers of a system are not independent products that happen to be stacked. Each is formulated to bond to the one below and to be overcoated within a stated interval, and the performance figures published for the system belong to that combination.
ISO 12944-5 describes systems in exactly these terms: family, number of coats, thickness, and the durability they are credited with for a given corrosivity category.
Sources and references
- StandardISO 12944-5:2019 — Paints and varnishes — Corrosion protection of steel structures by protective paint systems — Part 5: Protective paint systemsInternational Organization for Standardization · accessed August 29, 2026
- StandardSSPC-PA 2-2022 — Procedure for Determining Conformance to Dry Coating Thickness RequirementsAMPP · accessed August 29, 2026
Where this is covered in depth
- Anti corrosion coating types: choosing by exposure zoneFive coating families, and the order that picks between them: corrosivity category first, durability class second, product last.
- How to Read an Industrial Coating Technical Data Sheet (TDS)Stop getting fooled by marketing claims. Learn the 8 critical points to check on any industrial coating Technical Data Sheet (TDS) before you specify it.