ISO 2812-3:2019

Overview

ISO 2812-3:2019 - Paints and varnishes - Determination of resistance to liquids - Part 3: Method using an absorbent medium specifies a laboratory test method to assess how single- or multi-layer coating systems resist exposure to liquids or paste-like products. The standard uses an absorbent medium (filter paper or lint‑free cotton) soaked with the test substance, placed on coated test panels, and covered (watch glass or Petri dish) to simulate localized exposure. Results help determine coating damage and, where relevant, substrate effects.

Key topics and requirements

• Scope and principle: Determines effects of liquid/paste-like substances on coatings using an absorbent medium; assessment follows agreed criteria.
• Apparatus and materials: ordinary lab equipment plus air oven (up to 40 °C), watch glasses, Petri dishes, filter paper (depth filter sheets recommended), lint‑free cotton wool.
• Test substances: One or more agreed liquids or pastes. Annex A lists typical examples: automotive fuels and fluids, laboratory chemicals (ethanol, isopropanol, dilute acids/alkali), biological substances (simulated bird droppings, resins).
• Test panels and preparation: Use ISO 1514 standard panels (≈150 × 100 mm), coat and condition per ISO 1513, measure dry-film thickness per ISO 2808.
• Procedure essentials:
  • Condition panels at (23 ± 2) °C and (50 ± 5) % RH for ≥16 h (ISO 3270).
  • Perform tests in duplicate at standard temperature (23 ± 2) °C unless otherwise agreed.
  • Impregnate filter paper/cotton with test liquid, place on panel, cover, and expose for the agreed duration; for viscous/paste substances apply ~0.5 cm under the absorbent medium.
  • Clean and evaluate immediately and (unless otherwise agreed) again after 24 h.
• Evaluation and reporting: Assess blistering and other changes per ISO 4628-1/2; include full test report details (sample ID, panel prep, coating thickness, test substances, duration, temperature, results, tester, deviations).

Applications and users

ISO 2812-3:2019 is used by:

• Paint and varnish manufacturers and coating formulators for product development and QA.
• Independent test laboratories performing conformity and performance testing.
• Automotive and industrial coatings specifiers validating resistance to fuels, oils, cleaners, and biological contaminants.
• Procurement/specification writers requiring standardized test evidence for durability claims.

Keywords: ISO 2812-3:2019, paints and varnishes, resistance to liquids, absorbent medium, coating test method, test panels, filter paper, automotive coatings.

Related standards

• ISO 1513 (sample prep), ISO 1514 (standard panels), ISO 2808 (film thickness), ISO 3270 (standard conditioning), ISO 4628-1/2 (evaluation of degradation).