Overview
ISO 28199-3:2021 - Paints and varnishes: Evaluation of properties of coating systems related to the spray application process - Part 3 provides standardised, reproducible methods to assess defects and optical coverage that occur when coatings are applied by spray. The document (second edition, 2021) specifies visual and instrumented methods to evaluate tendency to sagging, bubble formation, pinholing (and cratering), and hiding power on spray-applied test panels under defined conditions. The standard is intended for use after drying/curing and links film-thickness measurements to defect limits.
Key topics and technical requirements
- Scope and testing basis
- Assessment is made on test panels prepared per ISO 28199-1 and film thickness measured in accordance with ISO 28199-1 (and related film-thickness standards).
- Evaluations are done after drying/curing of the coating.
- Tendency to sagging
- Visual or measured determination of runs/sags; example criterion: identify the hole where a sag exceeds 10 mm and record corresponding film thickness.
- Bubble formation
- Determine the bubble formation limit (film thickness where bubbles start to appear) visually or with measuring techniques in the wedge measurement area.
- Annex A includes photographic and 3‑D profile examples of bubbles.
- Pinholing and cratering
- Distinguishes pinholes from craters; assess the pinholing limit after curing and record film thickness at which pinholes occur. 3‑D photographs and profiles are provided.
- Hiding power
- Assessment of “black/white” hiding power is made after curing in accordance with ISO 6504-3, measured in the wedge/contrast-strip area.
- Reporting
- Test report requirements refer to ISO 28199-1, Clause 12.
- Measurement techniques
- The 2021 revision added instrumented measuring techniques for all evaluations and included 3‑D imaging as informative examples.
Applications and who uses it
- Practical applications
- Product development, quality control, production validation, process optimisation, and failure analysis for spray-applied coatings.
- Particularly relevant for automotive coatings, industrial finishes, plastics coatings, and any application where spray process parameters and film thickness affect defect formation and hiding.
- Typical users
- Coating formulators, R&D laboratories, quality engineers, applicators, test laboratories, and OEM specifiers.
Related standards
- ISO 28199-1:2021 - Vocabulary and preparation of test panels (normative reference)
- ISO 6504-3 - Determination of hiding power (black/white)
- ISO 2808 - Determination of film thickness
- ISO 4618 - Terms and definitions (paints and varnishes)
- ISO 28199-2 - Related evaluations (colour stability, wetting, mottling, etc.)
- ISO 18314-1 - Colour measurement
Keywords: ISO 28199-3, paints and varnishes, spray application, sagging, bubbles, pinholing, hiding power, film thickness, coating test methods, visual assessment, measuring techniques.
Open preview (PDF)Paints and varnishes — Evaluation of properties of coating systems related to the spray application process — Part 3: Assessment of sagging, formation of bubbles, pinholing and hiding power