Overview
EN ISO 22553-8:2021 - "Paints and varnishes - Electro-deposition coatings - Part 8: Electric charge density" specifies a laboratory method to determine the electric charge density of electro-deposition coatings (e‑coat). Adopted from ISO 22553-8:2020, this CEN standard targets automotive and general industrial applications (e.g., chiller units, radiators, consumer products, aerospace, agriculture). The electric charge density (expressed in coulombs per cubic metre, C·m⁻³) provides a quantitative indicator of deposition efficiency during e-coating.
Key topics and technical requirements
- Scope and purpose: Measurement of volume electric charge density to characterise e-coat deposition performance.
- Test panels and area: Electrically conductive panels, approx. 190 × 105 × 0.75 mm; masked coating area ≈ 280 cm² (both faces). Exact area must be recorded.
- Apparatus: Laboratory deposition system with tank recirculation and DC power supply, amperemeter, thermometer (±0.1 °C), film-thickness device (±0.1 µm), analytical balance (0.0001 g), controlled oven.
- Deposition procedure: Panels immersed in homogenized bath, deposition run between minimum and critical current densities; voltage/time selected to achieve nominal dry-film thickness. Rinsing with demineralized water and stoving (object temperature) follow deposition.
- Measurements and calculations: Dry-film thickness measured at five locations per side (ISO 2808 methods), panel mass before/after coating used to calculate charge density. Standard provides methods to express charge density per unit mass and per unit volume; Annex A covers calculations using practical or theoretical dry-film density (ISO 3233-2 / ISO 3233-3).
- Quality controls: Duplicate determinations recommended; stoving temperature, bath temperature control, and precision limits for instruments are specified.
Applications and who uses this standard
- Quality assurance teams in automotive and industrial coating operations use this standard to verify deposition efficiency and process reproducibility.
- Process engineers and R&D laboratories apply the method to optimize bath chemistry, current density and curing schedules.
- Coating formulators and suppliers use charge-density data to compare formulations and ensure consistent coverage.
- Certification and compliance personnel rely on standardized test results for supplier evaluations and contract specifications.
Related standards
EN ISO 22553-8:2021 is a practical, prescriptive method for laboratories and industry stakeholders who need reproducible, comparable measurements of electric charge density to control and improve e-coat processes.
