Overview
ISO 10216:2024 - "Anodizing of aluminium and its alloys - Instrumental determination of image clarity of anodic oxidation coatings - Instrumental method" defines a laboratory method to quantify image clarity and optical evenness of anodic oxidation (anodized) coatings on aluminium and its alloys. The fourth edition (2024) updates the light source and photometer requirements and adds the light source to the test report. The standard uses an optical comb (sliding combed shutter), slit optics and a photometer to measure surface reflection and light scattering from flat, reflective specimens.
Key topics and technical requirements
- Scope: Instrumental measurement of image clarity and optical evenness of anodic oxidation coatings on flat aluminium surfaces.
- Measurement principle: A slit illuminated and collimated, reflected at 45° from the specimen, is focused onto a combed sliding shutter; the photometer records variations as the shutter slides to determine clarity.
- Apparatus essentials:
- Slit: 0.02 mm ± 0.01 mm width, ~20 mm length.
- Lenses: focal length ≈ 130 mm.
- Combed sliding shutter: transparent/opaque ratio 1:1 with selectable slit widths (0.125, 0.25, 0.5, 1.0, 2.0 mm). (0.125 mm for mirror finishes; 0.5 mm for general use.)
- Photometer and light source: spectral response matched to the photopic standard V(λ) (CIE standard observer) and operated under CIE illuminant A or D65 conditions.
- Specimen handling: Representative flat area (standard size ~50 × 50 mm), free of contaminants; avoid edges and ensure treatment history matches product.
- Procedure highlights: Baseline with black glass, sensitivity adjustment using the specimen, measurements at two or more points and, if directional, in longitudinal and transverse orientations.
- Results: Image clarity is reported as a percentage derived from maximum and minimum light intensities; optical evenness is the ratio of longitudinal to transverse clarity; dispersion of light characterizes scattering.
Applications and users
ISO 10216:2024 is used for:
- Quality control and acceptance testing in anodizing plants and contract coatings.
- Laboratory verification by materials testing and surface metrology labs.
- Dispute resolution where instrumental measurement is preferred over visual assessment.
- Specification and procurement by OEMs, architects, automotive, aerospace and electronics industries where surface appearance and reflectivity matter.
- Process optimization and R&D for coating formulators and surface finish engineers.
Related standards
- ISO 10215 (visual chart scale using optical comb)
- ISO 7583 (terms and definitions for anodizing)
- ISO 7668 (specular reflectance and gloss measurement)
- ISO/CIE 11664‑1 and 11664‑2 (colorimetry and standard illuminants)
Keywords: ISO 10216:2024, anodizing of aluminium, image clarity, anodic oxidation coatings, instrumental method, optical evenness, specular reflectance, surface quality, photometer.
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