Overview
ISO 10308:2006 - Metallic coatings - Review of porosity tests is an ISO review standard that surveys published methods for detecting pores and discontinuities in a wide range of metallic and inorganic coatings. It covers techniques applicable to coatings such as chromium, nickel (and nickel alloys), copper, gold, silver, tin, zinc, enamel and conversion coatings, on substrates including aluminium, steel, copper alloys, magnesium, nickel and zinc alloys. The standard explains the principles behind porosity detection, typical specimen considerations and the observable reaction products used to reveal pores.
Key topics and requirements
- Purpose: reviews methods that reveal pores/discontinuities by producing an observable reaction product where the substrate is exposed.
- Test nature: porosity tests are generally short-duration and often destructive; they must clean, depolarize and activate the exposed substrate without attacking the intact coating.
- Interpretation: results are relative to the chosen method and magnification; reports should follow evaluation guidance (see Annex B).
- Examples of specific tests reviewed:
- Alizarin and anthraquinone tests (for coatings on aluminium and alloys)
- Cadmium sulfide and various electrographic (paper/gel) tests
- Copper sulfate (Preece and Dupernell variants) for ferrous and aluminium substrates
- Corrodkote (CORR), ferrocyanide/ferroxyl, permanganate and many wet-chemical indicators
- Salt spray variants (NSS, AASS, CASS) and sulphur-containing vapour tests
- Ancillary content: Annexes include tabular summaries of tests, typical reporting and evaluation, pore type schematics, discontinuity classification and a substrate/coating test index.
- Safety note: the standard warns that many reagents/procedures can be hazardous; proper precautions and legal obligations apply.
Applications and users
ISO 10308:2006 is useful for organizations needing an authoritative overview of porosity detection techniques for metallic coatings. Typical users:
- Coating process engineers and plating shops establishing quality-control programs
- QA/QC and corrosion testing laboratories selecting suitable porosity tests
- Product designers and procurement/spec writers specifying inspection requirements for plated or coated parts
- Aerospace, automotive, electronics, decorative finishes and surface‑treatment industries concerned with coating integrity and corrosion initiation
Practical benefits include selecting an appropriate porosity test for a given coating/substrate combination and understanding test limitations (destructiveness, sensitivity, and interpretation).
Related standards
- ISO 2080: Electroplating and related processes - Vocabulary (terms referenced)
- ISO 10289: Rating of test specimens and articles subjected to corrosion tests
- Other standards cited within ISO 10308 (examples): ISO 4524‑3, ISO 2085, ISO 1456, ISO 4541 - for detailed procedures of particular porosity methods.
Keywords: ISO 10308:2006, porosity tests, metallic coatings, coating porosity, porosity testing, electroplating porosity, corrosion testing, coating quality control.
