Overview
EN ISO 18771:2020 - Anodizing of aluminium and its alloys - specifies a practical laboratory and production-control method to determine the surface abrasion resistance of anodic oxidation coatings produced by sulfuric acid anodizing. Primarily intended for external architectural coatings, the standard uses glass-coated abrasive paper rubbed on the anodic surface to assess whether the coating is more or less wear resistant than the abrasive. The procedure is simple, largely operator‑dependent, and non‑destructive for coatings that pass the test.
Key Topics and Requirements
- Scope: Tests abrasion resistance of anodic oxide films on aluminium and its alloys (sulfuric acid anodizing), mainly for architectural applications.
- Apparatus:
- Validated glass-coated abrasive paper (Annex A validation procedure).
- Resilient support block (recommended 6–8 mm thick, ~30 × 40 mm) with hardness 30–70 IRHD (see ISO 48-2).
- Thickness measurement by eddy-current meter (ISO 2360) for Method 2.
- Note: fine glass grit ~P240 (ISO 6344-1) can be suitable.
- Test methods:
- Method 1 - Wrap abrasive paper around the block and make 10 double strokes (25–30 mm amplitude). Examine abrasive for chalky white powder: dense deposit = coating softer than glass; no deposit = coating more wear resistant.
- Method 2 - Make 50 double strokes, renewing abrasive area every 10 strokes; measure coating thickness in the abraded track. A loss > 2 µm indicates the coating is less wear resistant than the abrasive.
- Operator role: Production control method that relies on operator experience and instruction - sample preparation, consistent pressure, and track repeatability are important.
- Test report must reference ISO 18771 and include specimen ID, method used, abrasive details (manufacturer, product/lot), test location on the surface, result, and date.
Applications and Users
- Practical for anodizing plants, quality control laboratories, and coating manufacturers performing routine production checks.
- Useful to architects, specifiers, façade contractors, and materials engineers evaluating weathering resistance and comparative wear performance of anodized finishes.
- Beneficial when selecting or validating sealing and process parameters that affect surface hardness and chalking propensity.
Related Standards
- ISO 2360 - coating thickness (eddy-current)
- ISO 48-2 - rubber hardness (IRHD)
- ISO 2143, ISO 3210 - anodizing quality/sealing assessments
- ISO 7583 - anodizing terms and definitions
- ISO 8251 - abrasive wheel wear test (referenced for wear index comparison)
Keywords: EN ISO 18771:2020, anodizing, aluminium, abrasion resistance, glass-coated abrasive paper, surface abrasion test, sulfuric acid anodizing, architectural coatings, quality control.