Overview
EN ISO 15710:2006 - Paints and varnishes: Corrosion testing by alternate immersion in and removal from a buffered sodium chloride solution (ISO 15710:2002) - defines a laboratory method to assess the corrosion-protection performance of paint and varnish coatings on aluminium and aluminium alloys. The method simulates cyclic wet/dry exposure by alternately immersing coated, scribed test panels in a buffered sodium chloride solution and then exposing them at high humidity, giving reproducible comparative data on coating resistance to scribe-initiated corrosion.
Key topics and technical requirements
- Test principle: Alternate immersion/emersion cycles at controlled temperature and humidity; evaluation of corrosion propagation from a scribe through the coating.
- Test solution composition (initial):
- Sodium chloride: 30 g/L
- Disodium hydrogen orthophosphate: 0.19 g/L
- Boric acid: 1.25 g/L
- Target pH: 8.0 ± 0.2 (measured at 25 °C)
- Water purity per ISO 3696; salts must meet specified purity limits (total impurities ≤ 0.5 %, iodide ≤ 0.1 %, Cu/Ni ≤ 0.001 %).
- Test cabinet conditions:
- Temperature: 35 ± 2 °C
- Relative humidity: > 80 % during emersion periods (unless otherwise agreed)
- Immersion cycle: typically 2 hours immersed / 2 hours removed, repeated for the test duration (can be specified by agreement).
- Apparatus and volumes:
- Individual solution tanks sized to provide at least 4 mL of solution per cm² of panel surface.
- Test panels and scribe preparation:
- Aluminium panels, nominal 100 × 40 × 0.8 mm (unless agreed otherwise).
- Two scribe marks, ≥20 mm long, 0.6 ± 0.1 mm wide, depth 0.05–0.1 mm into substrate; orientation and method of scribing must be reported.
- Sample conditioning and measurements:
- Evaluation: Corrosion assessment around the scribe using agreed criteria, with reference to ISO 4628-8 for corrosion evaluation.
Applications and who uses it
- Primary use: Assessment of paint/varnish systems for aerospace applications (method was developed principally for aircraft coatings).
- Secondary use: Comparative laboratory testing by coating manufacturers, quality control laboratories, material engineers, and specifiers who need reproducible data on coating resistance to cyclic salt exposure and scribe-induced corrosion.
- Provides a controlled, reproducible way to compare formulations, validate coating systems, and monitor production quality.
Related standards
This standard is essential when you need a repeatable, documented laboratory method for evaluating corrosion protection of coatings on aluminium under alternate immersion conditions using a buffered NaCl solution.