Overview
ISO 8502-3:2017 - Preparation of steel substrates before application of paints and related products - Part 3 - describes a qualitative, pressure-sensitive tape method for assessing dust on steel surfaces prepared for painting. The standard provides pictorial quantity ratings and descriptive dust size classes to evaluate the average quantity and particle size of dust remaining after cleaning. The method can be used as a pass/fail inspection or to create a permanent record of surface dust prior to coating.
Key topics and technical requirements
- Principle: Press a piece of pressure-sensitive adhesive tape onto the steel surface, remove it, mount on a contrasting display board and visually assess dust coverage and particle size.
- Apparatus & materials
- Adhesive tape: transparent, 25 mm width, peel strength ≥ 190 N/m (IEC 60454-2 test).
- Display board: contrasting colour (e.g., black or white glazed tile, card or paper).
- Spring-loaded roller: calibrated to apply ~39.2 N or 49.0 N (Annex A) or manual thumb application.
- Hand lens: ×10 magnification.
- Procedure highlights
- Discard first three turns of tape; use ≈200 mm tape length and press ≈150 mm onto surface.
- Apply pressure by thumb or calibrated roller, moving three strokes each direction, each stroke taking 5–6 s.
- Compare tape to pictorial references to assign a quantity rating (1–5); use Table 1 to assign a size class (0–5) (class 1: <50 μm; class 2: ~50–100 μm; class 3: up to 0.5 mm; classes 4–5 larger).
- Minimum three tests per surface; additional tests if results vary.
- Limitations: Qualitative and subjective; not suitable for deep pits (surfaces corresponding to rust grade D). Use calibrated roller in dispute cases.
Applications and users
- Use cases
- Site inspection before applying protective coatings to steel (bridges, ship hulls, offshore structures, pipelines, industrial equipment).
- Quality control for blast-cleaning and other surface preparation processes.
- Contractual pass/fail verification and archival records of pre-paint cleanliness.
- Who benefits
- Coating specifiers, inspection engineers, contractors, third‑party QA inspectors, asset owners, and maintenance teams seeking to reduce coating failures linked to dust contamination.
Related standards
- ISO 8501-1 - Rust grades and preparation grades (used to define applicability for rust grades A, B, C).
- ISO 4628-1 - Basis for quantity ratings and size class derivation.
- IEC 60454-2 - Test method for pressure-sensitive adhesive tape peel strength.
- Note: ISO 8502-3 is part of the ISO 8502 series on tests for surface cleanliness and complements ISO 8503/8504 guidance on surface roughness and preparation.
Keywords: ISO 8502-3:2017, dust assessment, pressure-sensitive tape method, surface cleanliness, steel substrate, pre-paint inspection, dust particle size, blast-cleaned steel.