EN ISO 3210:2025 PDF

Overview

EN ISO 3210:2025 - "Anodizing of aluminium and its alloys - Assessment of quality of sealed anodic oxidation coatings by measurement of the loss of mass after immersion in acid solution(s)" is a CEN-adopted ISO standard that specifies two destructive test methods to assess the surface quality of sealed anodic oxidation (anodized) coatings on aluminium and its alloys. The evaluation is based on measurement of mass loss after immersion in phosphoric-acid-based test solutions. The 2025 edition supersedes EN ISO 3210:2017 and updates limits for dissolved coating/aluminium in test solutions.

Key Topics

• Two test methods
  • Method 1: Immersion in a phosphoric-acid based solution without prior acid predip - suitable for decorative/protective coatings and applications where staining resistance matters.
  • Method 2: Immersion after a predip acid treatment (nitric acid predip) - intended for more severe, outdoor architectural applications.
• Test solutions
  • Test solution A: Phosphoric acid + chromium(VI) oxide (contains Cr(VI); use B when possible).
  • Test solution B: Phosphoric acid only (recommended when Cr(VI) can be avoided).
  • Predip for Method 2: Nitric acid solution (specified concentration).
• Scope and exclusions
  • Not applicable to hard-type anodic coatings (typically unsealed), coatings sealed only in dichromate solutions, coatings produced in chromic acid, or coatings rendered hydrophobic.
• Principle and limitations
  • Surface-specific test: a well-sealed coating resists acid attack; the methods assess surface resistance, not through-thickness integrity.
  • Destructive methods intended as reference tests in case of dispute with nondestructive tests (e.g., ISO 2143 loss of absorptive power, ISO 2931 admittance).
• Test practice essentials
  • Use analytical-grade reagents, deionized water, and a balance with 0.1 mg readability.
  • Test specimen surface area guidance: approx. 1 dm² (minimum 0.5 dm²); specimen mass ≤ 200 g.

Applications

• Quality control and acceptance testing for anodized aluminium in:
  • Architectural façades and external building components (Method 2).
  • Decorative panels, consumer goods, and parts requiring stain resistance (Method 1).
• Use by anodizers, QA laboratories, materials engineers, specifiers, façade consultants, and procurement teams to verify sealing performance and support dispute resolution.
• Reference method when nondestructive tests give uncertain results.

Related Standards

• ISO 2143 - Test for loss of absorptive power (nondestructive reference).
• ISO 2931 - Measurement of admittance (nondestructive reference).
• ISO 7583 - Terms and definitions for anodizing of aluminium.

Keywords: EN ISO 3210:2025, anodizing, sealed anodic oxidation coatings, loss of mass test, phosphoric acid, Method 1, Method 2, hydrothermal sealing, aluminium alloys, quality assessment.