Heavy dust coverage, coating application should not proceed. 2. Particle Size Classes (0–5) The average particle size is designated by a class: Size 0: Particles invisible to the naked eye (microscopic).
Always ensure you are using the revision, obtain the official PDF for legal traceability, and carry a laminated reference card for daily field use.
Many coating inspectors use a from:
The is an indispensable tool for any coating inspector, contractor, or engineer. Understanding the difference between Class 1, 2, and 3—and correctly applying the pressure-sensitive tape method—can mean the difference between a 20-year coating lifespan and a 6-month failure.
The standard utilizes a qualitative "pressure-sensitive tape method". A strip of specialized adhesive tape—typically 200 mm long—is pressed onto the prepared steel surface. Pressure is applied either manually with a thumb or, for greater accuracy in disputes, using a calibrated spring-loaded roller to ensure consistent force. Once removed, the tape is mounted on a contrast-colored board (usually black or white) for visual evaluation. Understanding the ISO 8502-3 Rating Chart The evaluation is split into two distinct categories: Particle Size INTERNATIONAL STANDARD ISO 8502-3 iso 85023 dust level chart pdf updated
For assessing Class 1 and Class 2 particles and Rating 0 surfaces.
- Surface identification: [tank, pipe, beam] - Cleaning method: [garnet, slag, steel grit] - Dust assessment date & time: - Ambient conditions (humidity, temp): - Tape brand & batch number: - Sample locations (grid or sketch): - Dust class per ISO 8502-3:2017: _____ - Largest particle size observed: _____ µm - Inspector name & signature: Heavy dust coverage, coating application should not proceed
Large particles between 0.5 mm and 2.5 mm in diameter.
: Trace to light dust (often acceptable for high-performance coatings). Always ensure you are using the revision, obtain