ISO 12944
ISO 12944 explained: protecting steel with paint systems
The standard behind most protective coating specifications for steel. Corrosivity categories, durability classes and what each part covers.
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Resources
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Standards guides
ISO 12944, ISO 8501 and more, in plain English.
Coating defect library
What each defect looks like, why it happens, how to prevent it.
Insights
Practical articles on inspection, specification and quality.
Dew point calculator
Check steel temperature against the dew point on site.
Popular guides
Start with the standards
ISO 8501-1
ISO 8501-1: surface preparation grades Sa 2½, St 3 and more
The visual standard for steel cleanliness before painting. Rust grades, blast cleaning grades and hand or power tool grades.
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ISO 8502: dust, soluble salts and dew point before painting
The tests for what you cannot see: dust, soluble salt contamination and the risk of condensation on the steel.
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Defect library
The defects we see most
Blistering: bubbles under or within the coating
Dome-shaped bubbles in the film, often caused by contamination trapped under the coating that draws in water.
ReadCissing and cratering: coating that will not wet the surface
Round craters or bare patches where the coating has pulled away from a contaminated spot.
ReadFlash rust and rust spotting
A light orange haze on freshly prepared steel, or rust spots breaking through a finished coating.
ReadMud cracking: a crazed pattern like dried mud
A network of cracks like a dried riverbed, most often in zinc-rich primers applied too thickly.
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