Overview
ISO 2812-5:2018 specifies the temperature‑gradient oven method for assessing the resistance of single‑layer or multi‑layer paint and varnish systems to liquids and paste‑like substances. The method exposes coated test panels to controlled droplets of test liquids across a linear temperature gradient, enabling determination of the temperature at which the coating first shows visible change and (if required) any substrate damage.
Key topics and requirements
- Test principle: Apply defined droplets of test substance to a coated panel, insert horizontally into a gradient oven, expose, clean and visually assess for first visible change.
- Gradient oven: Heats the substrate from the bottom to produce a linear temperature gradient (typical setting 35 °C to 80 °C). Gradient specification: 1 °C increase per 1.0 cm along the panel; maximum cross‑width gradient ≤ 2.5 °C. Heating bench design must ensure homogeneous heat transfer.
- Test panels and coating:
- Typical substrate: steel panels ~560 mm × 100 mm, 0.7–1.0 mm thick.
- Coatings prepared per ISO 1514; dry film thickness measured per ISO 2808.
- Condition panels ≥16 h at (23 ± 2) °C and (50 ± 5)% RH (ISO 3270) immediately before testing.
- Test substances and volumes: Use one or more agreed liquids (examples in Annex A include 5% NaOH, 10% HCl, sulfuric acid solutions, water, resins, honey, simulated bird droppings). Droplet volumes typically 25–100 µl depending on substance.
- Procedure parameters:
- Apply droplets at room temperature (18–28 °C) on a lab bench, then insert panel and press to the heating bench.
- Standard exposure: 30 minutes (unless otherwise agreed).
- Clean residues (water or suitable solvent) and assess visually per ISO 13076; reassess after 24 h if not otherwise agreed.
- Reporting and precision:
- Report the temperature of first visible change and full test details (substrate, coating application, film thickness, test substances, gradient, deviations).
- Precision: repeatability r = 4 °C (±2 °C), reproducibility R = 8 °C (±4 °C).
Applications and users
ISO 2812-5 is used to:
- Evaluate chemical and biological liquid resistance of industrial, automotive, marine and architectural coatings.
- Screen formulations during R&D for improved solvent, acid/base and biological‑stain resistance.
- Support quality control, specification compliance and comparative performance claims.
Typical users:
- Coating manufacturers, formulation scientists and R&D labs
- Quality assurance and testing laboratories
- Specifiers and procurement teams evaluating coating durability
Related standards
Normative references include ISO 1513, ISO 1514, ISO 2808, ISO 3270, ISO 4618, ISO 13076 and ISO 15528 - these cover sample prep, panels, film thickness, conditioning, terminology and visual assessment procedures.
Open preview (PDF)Paints and varnishes — Determination of resistance to liquids — Part 5: Temperature-gradient oven method