Overview
ISO 22553-8:2020 - 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-coats). The standard is targeted at automotive and general industrial applications (chillers, consumer products, radiators, aerospace, agriculture) and defines how to measure charge required to deposit a given mass or volume of cured coating.
Key topics and technical requirements
- Scope and purpose: Measures the efficiency of the e‑coat deposition process by quantifying electric charge per mass or per volume of cured film.
- Test system: Uses a laboratory deposition system (deposition tank, recirculation, DC supply, anode/cathode arrangement), with controlled bath temperature and stirring.
- Test specimens: Electrically conductive test panels (approx. 190 × 105 × 0.75 mm) masked to a defined coated area; each determination carried out in duplicate.
- Sample preparation & procedure:
- Weigh panels before deposition, immerse in e‑coat bath, apply specified voltage/current between minimum and critical current density, rinse and stove/cure.
- Measure dry‑film thickness at five locations per side (ISO 2808 methods) and reweigh panels to obtain deposited dry mass.
- Maintain controlled stoving temperature (object temperature) and bath temperature (typ. 25–35 °C unless specified).
- Calculations:
- Electric charge density per unit mass (C/g) - charge required to produce 1 g dry mass of coating (uses difference between coated and uncoated panel masses and measured electrical charge).
- Electric charge density per unit volume (C/cm³ or converted to C/m³) - uses total coated area and dry‑film thickness to compute film volume and relates total charge to that volume.
- Annex A provides options using practical or theoretical dry‑film density/thickness (ISO 3233‑2 / ISO 3233‑3) when applicable.
- Instruments: amperemeter, thermometer (±0.1 °C), film‑thickness gauge (±0.1 µm), analytical balance (±0.0001 g), oven (specified tolerances).
- Reporting: Requires full test conditions and results (voltage, temperature, current, charge, stoving details, thickness method, coated area, deviations, anomalies). Precision data is currently not available.
Applications and who uses it
- Coating formulators and R&D labs use the method to optimize bath formulations and deposition parameters.
- Automotive OEMs and suppliers apply the standard for process control and comparative performance of e‑coats.
- Quality assurance and factory labs use it to validate deposition efficiency, troubleshooting, and material acceptance.
- Regulatory/compliance teams reference it when specifying test requirements in procurement or technical specifications.
Related standards
Keywords: ISO 22553-8:2020, electric charge density, electro-deposition coating, e-coat, film thickness, charge per unit mass, laboratory deposition system, automotive coatings.
Open preview (PDF)Paints and varnishes — Electro-deposition coatings — Part 8: Electric charge density