Overview
EN ISO 23321:2020 (ISO 23321:2019) specifies properties and test methods for demineralized water used as a solvent in industrial paints and varnishes. It is intended for production processes such as electro-deposition coatings, water‑based coating materials, water‑based resins and plastics dispersions. This document is produced by CEN adopting the ISO text and is not applicable to water for analytical laboratory use (see ISO 3696).
Key compliance points include:
- Appearance: clear, without foreign matter
- Electrical conductivity at 25 °C: maximum 20 µS/cm (ISO 15091)
- pH at 23 °C: 5 to 8 (ISO 19396-1 / ISO 19396-2)
- Chloride content: maximum 3 mg/l (ISO 10304-1)
- Evaporation residue (2 h at 110 °C): maximum 5 mg/kg (see ISO 3696)
- Colony content: colony forming units (CFU) - no findings; Clause 5 gives an example test-strip/contact-slide method
Key Topics
- Specification limits: The standard sets quantitative limits for conductivity, pH, chloride and evaporation residue to ensure consistent solvent performance in coatings manufacture.
- Microbiological control: Clause 5 provides an example procedure for determining colony content (sampling, sterilization of taps, incubation and evaluation). The standard allows use of other suitable microbiological methods where appropriate.
- Referenced test methods: The document references established ISO methods for conductivity, pH, anion determination and sampling for microbiological analysis, enabling harmonized testing across suppliers and production sites.
- Reporting requirements: A standard test report structure is defined to ensure traceability and uniform communication between suppliers and users.
Applications
EN ISO 23321:2020 is intended for manufacturers, quality laboratories and procurement teams involved in:
- Production of electro-deposition (e-coat) materials
- Formulation and manufacture of water‑based coatings and varnishes
- Manufacture of water‑based resins and plastic dispersions
- Incoming quality control of demineralized water used as solvent
Benefits of applying the standard:
- Reduced variability in coating performance due to water quality
- Clear acceptance criteria for suppliers and internal QC
- Aligned testing and reporting across sites and supply chains
Related Standards
- ISO 3696 - Water for analytical laboratory use (referenced for evaporation residue)
- ISO 15091 - Determination of electrical conductivity and resistance
- ISO 19396-1 / ISO 19396-2 - pH electrode methods for paints and varnishes
- ISO 10304-1 - Determination of dissolved anions (chloride)
- ISO 19458 - Water quality - Sampling for microbiological analysis (informative for sampling technique)
Use EN ISO 23321:2020 to establish reproducible quality of demineralized water in coating production, reduce process risk, and harmonize acceptance criteria between suppliers and manufacturers.
