ISO 28706-3:2017

Overview

ISO 28706-3:2017 defines a laboratory test method to evaluate the resistance of vitreous and porcelain enamels to chemical corrosion by alkaline liquids. The standard covers testing at temperatures from 25 °C to 95 °C using either a hexagonal vessel (six specimens) or a tetragonal glass bottle (four specimens). Results are based on measured mass loss of enamelled specimens and, where appropriate, calculated as a rate of loss per unit area.

Key topics and requirements

• Test principle: Simultaneous exposure of multiple enamelled specimens to an alkaline liquid under controlled temperature and continuous stirring; determination of mass loss and expression of results.
• Apparatus: Hexagonal vessel for six specimens or tetragonal glass bottle for four specimens; laboratory glassware must meet referenced standards.
• Temperatures: Applicable test temperatures between 25 °C and 95 °C to simulate service or cleaning conditions.
• Test liquids: A standard detergent solution is specified to represent typical neutral-to-alkaline washing agents (components include sodium tripolyphosphate, sodium carbonate, sodium perborate and an alkylsulfonate wetting agent). The method also allows testing with other alkaline solutions.
• Result interpretation: Where corrosion proceeds linearly, a rate of mass loss per unit area and a corrosion rate (for example, mm/year) can be calculated. For many detergent tests the corrosion behaviour may be non-linear; therefore, results are often reported as mass loss per unit area with the test duration indicated (24 h, 168 h or as specified).
• Stirring and heating: Solution is introduced cold and heated in the vessel; stirring simulates washing-machine action and affects attack severity.
• Limitations: Test parameters are not appropriate for certain low-firing enamels (for example, enamels fired below 700 °C) unless modified conditions are agreed.

Applications and users

ISO 28706-3:2017 is used to:

• Verify chemical resistance of enamelled cookware, sinks, domestic appliance interiors and industrial enamel coatings against alkaline cleaners and detergents.
• Support quality control, product development and comparative performance testing of vitreous and porcelain enamels.
• Provide data for compliance testing by manufacturers, independent test laboratories, certification bodies and R&D teams evaluating cleaning/maintenance durability.

Practical benefits include reproducible evaluation of enamel durability under simulated washing or alkaline-exposure conditions and informed material selection for products exposed to detergents or alkaline environments.

Related standards

• ISO 28706 series (other parts cover acid and vapour tests, specimen production)
• ISO 28706-1, -2, -4, -5 as referenced in the ISO 28706 family for complementary corrosion test methods and conditions

Keywords: ISO 28706-3:2017, vitreous and porcelain enamels, chemical corrosion resistance, alkaline liquids, standard detergent solution, hexagonal vessel, tetragonal glass bottle, enamel corrosion testing.