The common language
of corrosion protection.
ISO 12944 is the international standard that defines the corrosion protection of steel structures by protective paint systems. It assigns the environment to a categoryand the expectation to a durability class — so instead of debating “good paint”, you discuss a measurable system.
Atmospheric corrosivity categories.
The standard's first question is: where does the structure stand? The category describes the load the environment places on the steel and determines the entire system.
Durability classes.
Durability is not a guarantee period; it is the system's expected life until the first major maintenance — in the same environment, a 7-year target and a 25-year target require an entirely different number of coats and film thickness.
Low
Up to 7 years
Temporary structures, short-term assets
Medium
7 – 15 years
Facilities with a planned maintenance cycle
High
15 – 25 years
Infrastructure, main production assets
Very high
Over 25 years
Hard-to-reach structures that are costly to maintain
Category + durability = system.
Select your corrosivity category and target durability; see the number of coats, total dry film thickness and surface preparation you will need.
What is the corrosivity level of the environment where your structure is located?
How long should the system last until the first major maintenance?
Select a corrosivity category and durability period to see the result.
High protection
This result is for guidance only. The final system selection depends on surface condition, application conditions and the existing coating. Let's confirm it with our free site inspection report.
Preparation grade is half the system.
Even the best coating will not adhere to an unprepared surface. ISO 8501-1 defines surface cleanliness grades; whatever grade the selected system requires, the site must comply with it.
St 2 — Hand tool cleaning
Loose rust and paint residue are removed. For repairs with limited life expectancy.
Sa 2 — Thorough blast cleaning
Most of the surface is cleaned; slight staining may remain. For low-category systems.
Sa 2½ — Very thorough blast cleaning
The de facto standard for industrial corrosion protection. Most C3–C5 systems require it.
Sa 3 — Blast cleaning to visually clean steel
The highest preparation grade. For CX and critical assets, beneath zinc-rich systems.
Solid foundation, robust barrier, durable finish.
Corrosion control
The secret of every durable coating lies in a solid primer layer that protects the metal surface from external influences and ensures the adhesion of the topcoat. High-solids zinc phosphate epoxy primers provide superior corrosion protection even in the harshest conditions.
Film thickness
Carries the system's total dry film thickness (DFT). This is the main barrier that delays moisture, ions and chemicals from reaching the metal; the higher the category, the thicker this layer.
Visible finish and last line of defence
The topcoat is the visible face of the system. As well as aesthetics, it forms the last line of defence against UV rays, chemicals and physical impact. The right choice determines both visual quality and durability.
In 2K (two-component) systems, mixing the base and the hardener starts a chemical reaction; the result is a surface that is much harder, more durable and more chemical-resistant than one-component paints. Mixing ratios and curing times are specified in the product's technical data sheet (TDS).
The standard is set in the laboratory, the result on site
ISO 12944-6 represents performance proven in the laboratory. The real result depends on the right system being applied correctly on site. Let us assess your existing system against this standard with our free site inspection report.
