Overview
ISO 16348:2003 - "Metallic and other inorganic coatings - Definitions and conventions concerning appearance" defines terminology and principles for validating the appearance of metallic and other inorganic coatings. Published in 2003, the standard sets out how appearance and related terms are to be interpreted and establishes the requirement to validate appearance when it is specified in product requirements.
Key topics and technical requirements
- Definitions: Clear terms such as appearance, uniformity of appearance, blemish, and visible defect are specified to ensure consistent interpretation across suppliers, manufacturers and inspection bodies.
- Principle of validation: When appearance is a specified requirement, a test to validate appearance is mandatory. The product standard should supply detailed validation methods; if it does not, a comparator method may be used.
- Representative approved reference samples:
- Approved reference samples must represent acceptable variations and be made/ coated using the same processes as production parts to ensure reproducibility.
- All interested parties should agree on reference samples and retain them for future inspection.
- Durability and storage of reference samples may require special measures (for example, desiccators or expiry dates).
- Measurement options: Instrumental techniques such as glossmeters, surface profiling, colour matching, and other suitable test methods may be used provided the required properties are specified by the product standard or purchase order.
- Inspection conditions: Lighting, angle of incidence, magnification and viewing distance must be agreed at enquiry/order time to avoid disputes.
- Test report minimum content: type of test/specification number; test conditions; details of article tested; examination/inspection conditions; any deviations from the product standard.
Applications and users
ISO 16348 is practical for:
- Coating manufacturers and finishers specifying or verifying cosmetic quality of metallic and inorganic coatings
- OEMs and component suppliers requiring consistent surface appearance across batches
- Quality assurance and inspection laboratories implementing referee or comparator methods
- Procurement and specification writers who need unambiguous appearance requirements in contracts and product standards
Use ISO 16348 when appearance is functionally or commercially important and when objective, reproducible validation and agreed reference samples are required.
Related standards
ISO 16348 references and complements other coatings standards addressing thickness, terminology and corrosion testing such as:
Keywords: ISO 16348, metallic coatings, inorganic coatings, appearance validation, reference samples, comparator method, glossmeter, inspection conditions.
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