Trace amounts; particles visible only under magnification. Rating 2: Dust barely visible to the naked eye. Rating 3: Particles clearly visible. Rating 4: Significant dust accumulation; easily noticeable. Rating 5: Heavy contamination. 2. Dust Size Classes (0–5)

Surface cleanliness is the foundation of any long-lasting protective coating. Dust on blast-cleaned steel can significantly reduce the adhesion of organic coatings and promote corrosion by trapping moisture. The ISO 8502-3 standard provides a standardized method to quantify and categorize this dust, allowing inspectors to make objective "pass/fail" decisions before paint application.

A preview of the ISO 8502-3:2017 standard is available via iTeh Standards.