Overview
EN ISO 28706-1:2011 (ISO 28706-1:2008) specifies a standardized laboratory test method to determine the resistance of vitreous and porcelain enamelled articles to chemical corrosion by acids at room temperature. Adopted by CEN as a European standard, this part of the ISO 28706 series defines how to expose enamel surfaces to acidic solutions, record effects and classify results for quality control, specification and comparison purposes.
Key topics and requirements
- Scope and principle: Describes the corrosion mechanism for enamel (silica network hydrolysis and leaching of constituents) and the rationale for room-temperature acid testing.
- Test solutions and reagents: Defines specific acid tests (notably citric acid and sulfuric acid at room temperature) and provides provisions for other acidic solutions. (See Clauses 9–11.)
- Materials and apparatus: Lists required equipment and specimen preparation methods to ensure reproducible exposure and measurement.
- Procedure: Specifies how specimens are attacked by the test solution, post-exposure determination and measurement steps (mass loss per unit area, visual examination).
- Classification and reporting: Requires classification of the enamel resistance based on measured effects and a standardized test report including test solution, test time, observed mass loss or visual changes and relevant test conditions.
- Interpretation of results: Notes that attack behaviour can be linear or logarithmic; for some conditions a corrosion rate (e.g., mass loss per unit area per time) can be calculated, while for others only mass loss and appearance are reported.
Practical applications and users
- Manufacturers of vitreous and porcelain enamel coatings - to validate product durability and support technical datasheets.
- Quality control and assurance teams - for incoming inspection and production lot verification.
- Independent test laboratories - to provide accredited acid resistance testing and certified reports.
- Product designers and specifiers - to select enamel grades suitable for acidic service environments.
- Regulatory bodies and purchasers - to compare materials against harmonized test criteria.
Typical practical outcomes include detection of staining, surface roughening or measurable mass loss; highly resistant enamels may show no visible change under the specified tests.
Related standards
- EN ISO 28706 series (Parts 2–5) - covers other acid and alkaline corrosion tests (boiling acids, alkaline liquids, closed systems, vapour-phase tests).
- EN 14483-1:2004 - superseded by EN ISO 28706-1:2011.
Keywords: EN ISO 28706-1:2011, ISO 28706-1:2008, vitreous enamel chemical corrosion, acid resistance test, porcelain enamels, citric acid test, sulfuric acid test, corrosion classification, mass loss per unit area.
