ISO 28199-3:2021

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.