EN ISO 21545:2020 (identical to ISO 21545:2018) specifies a standard laboratory method for the determination of settling in paints and varnishes (coating materials). The method quantifies short‑time settling - for example during transport or while in an electro‑deposition (electrocoat) bath - by measuring the volume of sediment that forms in a closed measuring cylinder over an agreed holding time.
Key topics and technical requirements
- Scope: Short‑time settling of coating materials; not a long‑term shelf‑life test.
- Principle: Allow a representative sample to stand in a graduated glass cylinder at room temperature and measure sediment height/volume after an agreed time.
- Sampling & preparation: Follow ISO 15528 (sampling) and ISO 1513 (sample preparation and stirring) before testing.
- Apparatus required:
- Laboratory stirrer.
- 100 ml (1 ml graduations) or 250 ml (2 ml graduations) measuring cylinder, accuracy class B per ISO 4788.
- Time measuring device with at least 30 s reading accuracy.
- Test conditions: Conduct test at room temperature (record actual temperature). Cylinder size and holding time must be agreed and reported.
- Procedure highlights:
- Clean and dry cylinder using suitable solvent.
- Fill to the specified volume mark and cap the cylinder.
- Let stand for the agreed holding period.
- Read sediment volume in millilitres and express as a percentage of total volume.
- Results & reporting: Test report must identify the product, reference ISO 21545, record temperature, cylinder size, holding time, result (sediment volume %), any deviations or unusual observations, and test date.
- Precision: No precision data are provided in this document.
Practical applications and users
- Who uses it: Paint and varnish manufacturers, QC laboratories, formulation and R&D teams, electrocoat operators, raw‑material suppliers and transport/logistics specialists concerned with product stability during handling.
- Why it’s useful: Provides a simple, repeatable short‑term settling test to:
- Detect rapid sedimentation that could affect application consistency.
- Assess stability during transportation or in electro‑deposition baths.
- Support QC acceptance criteria and batch release decisions.
- Limitations: This method measures short‑term settling only. For long‑term shelf stability, alternative tests (for example ASTM D869) are referenced.
Related standards
- ISO 1513 - Examination and preparation of test samples
- ISO 15528 - Sampling of paints, varnishes and raw materials
- ISO 4618 - Terms and definitions for paints and varnishes (defines “settling”)
- ISO 4788 - Laboratory graduated measuring cylinders (accuracy class)
- ASTM D869 - Alternative method for evaluating degree of settling (longer‑term/shelf tests)
Keywords: EN ISO 21545:2020, ISO 21545:2018, settling test, paints and varnishes, determination of settling, coating materials, measuring cylinder, short‑time settling, electrocoating.