Overview
EN ISO 10308:2006 - Metallic coatings: Review of porosity tests is an ISO/CEN review standard that surveys published porosity testing methods for a wide range of metallic coatings and conversion coatings. The standard (adopted as EN ISO 10308:2006) summarizes techniques used to reveal pores and other coating discontinuities that expose the substrate metal. It covers coatings such as chromium, nickel (and its alloys), copper, gold, silver, tin, zinc, anodized aluminium, vitreous enamel and many others on substrates including aluminium, brass, copper, steel, magnesium and nickel alloys.
Key topics and technical requirements
- Scope of application: Lists coatings and base metals to which the reviewed porosity tests apply.
- Principle of testing: Porosity tests rely on a chemical reaction with the exposed substrate at discontinuities to produce an observable reaction product; tests are usually short-duration and often destructive.
- Common test features: Cleaning/activation of substrate, limited reaction time to avoid undermining the coating, visual or microscopic examination (typical magnifications noted).
- Specific tests reviewed: Alizarin, Anthraquinone, Copper sulfate (Preece and Dupernell), Ferroxyl, Ferrocyanide, Polysulfide, Permanganate, Thioacetamide (TAA), salt spray variants (NSS, AASS, CASS), hot-water, sulfur dioxide/hydrogen sulfide and many more (see Annex A for tabular summary).
- Supporting material: Annexes include tables of porosity tests, typical reporting and evaluation criteria, pore types, classification of discontinuities and testing method classifications.
- Limitations: Results are method- and magnification-dependent; porosity counts are relative values. The standard includes a safety warning about hazardous reagents and procedures.
Applications and users
Who uses EN ISO 10308:2006:
- Quality/control engineers in electroplating and surface‑finishing shops
- Corrosion testing and metallurgical laboratories
- Coating process developers and R&D teams
- Inspectors, purchasers and specifiers writing coating acceptance criteria
- Industries where coating integrity is critical: aerospace, automotive, electronics, watchmaking, decorative and industrial hardware
Practical uses:
- Selecting appropriate porosity test methods for a given coating/substrate combination
- Interpreting porosity test results and preparing consistent test reports (Annex B guidance)
- Comparing methods (short-term/visual vs. electrographic/chemical) to define inspection protocols
Related standards
- ISO 2080 - Electroplating and related processes - Vocabulary
- ISO 10289 - Methods for corrosion testing - Rating of specimens subjected to corrosion tests
Note: EN ISO 10308:2006 is a review/reference document - it summarizes and cross-references established porosity tests rather than prescribing a single mandatory procedure.
