Overview
ISO 22553-13:2021 specifies a laboratory method to determine the re-solving (redissolution) behaviour of electro-deposition coatings (e-coat). The standard is intended for electro-deposition coatings used in automotive and other industrial applications such as chillers, consumer goods, radiators, aerospace and agricultural equipment. The method evaluates whether deposited e-coat films are prone to dissolve back into the coating bath or ultrafiltrate during processing and rinsing.
Why this matters: re-solving behaviour affects coating uniformity, film thickness, surface defects and overall process yield. ISO 22553-13 provides a repeatable procedure for quality control and formulation assessment.
Key Topics
- Scope and terms: Defines redissolution and ultrafiltration/ultrafiltrate as used in electro-deposition coating testing.
- Principle: Two pretreated conductive panels are coated in a laboratory deposition cell, exposed to the parent coating and to ultrafiltrate under controlled conditions, then cured and evaluated for changes in dry-film thickness and surface defects.
- Apparatus and tolerances:
- Laboratory deposition tank with recirculation and DC supply.
- Thickness gauge with maximum permitted error of 0.1 µm.
- Oven capable of maintaining specified bake temperatures within ±2 °C (to 150 °C) or ±3.5 °C (150–200 °C).
- Thermometer (±0.1 °C) and stopwatch (±1 s).
- Test panels: Electroconductive panels pretreated per ISO 1514, approx. 190 × 105 × 0.75 mm.
- Procedure highlights:
- Homogenize bath and set deposition voltage/time to achieve nominal dry-film thickness.
- After deposition and rinse, immerse portions of the coated panel sequentially in the e-coat bath and in the ultrafiltrate with agitation for defined periods without applied voltage, then rinse and cure.
- Measure dry-film thickness at three points per zone and perform visual inspection for surface defects (stripes, dissolution effects).
- Evaluation: Record mean dry-film thickness per zone and rate surface change intensity using the ISO 4628-1 scale (0–5).
Applications
- Routine quality control of e-coat formulations and process parameters in automotive and industrial coating lines.
- Comparative testing during R&D to assess susceptibility to re-solving when using ultrafiltration or rinse processes.
- Supporting supplier qualification and audits where coating stability and resistance to bath or ultrafiltrate exposure are critical.
Related Standards
- ISO 1514 - Standardized panels for coating tests
- ISO 2808 - Methods for dry-film thickness measurement
- ISO 4618 - Terms and definitions for paints and varnishes
- ISO 4628-1 - Assessment of coating degradation (designation and intensity scale)
- ISO 23321 - Demineralized water for industrial paint applications
For reporting, ISO 22553-13 requires inclusion of material identification, bath voltage and temperature, deposition and bake conditions, test results per Clause 9, deviations from the method and any unusual observations. This facilitates consistent, auditable records for coating performance and process control.
Open preview (PDF)Paints and varnishes — Electro-deposition coatings — Part 13: Determination of re-solving behaviour