Overview
ISO 2811-2:2011 - Paints and varnishes: Determination of density - Part 2: Immersed body (plummet) method specifies a standardized test for measuring the density of paints, varnishes and related products using an immersed body (plummet). Based on Archimedes' principle, the method is intended for low to medium viscosity materials and is particularly suited to production control and filling-machine monitoring. The reference test temperature is 23.0 ± 0.5 °C, and results are reported in grams per cubic centimetre (g/cm³).
Key topics and requirements
- Principle: Density ρ is calculated from the difference in balance readings before and after immersion of a calibrated plummet: rho = (m1 − m2) / V, where m1 and m2 are the appropriate mass readings and V is the plummet volume at the test temperature.
- Plummets: Non‑corrodible metal bodies (e.g., brass, stainless steel, aluminium), typically 10 cm³ or 100 cm³ volume, marked with volume, reference temperature and reference liquid data.
- Apparatus:
- Analytical balance accurate to 0.01 g (10 mg).
- Thermometer accurate to 0.2 °C.
- Temperature‑controlled chamber to maintain the specified test temperature (±0.5 °C).
- Tripod/retort stand and laboratory jack for immersion control.
- Procedures:
- Procedure A: Standard immersion for general paints.
- Procedure B: Modified set‑up for products containing fast‑evaporating solvents (retort stand + lab jack to limit evaporation).
- Calibration & temperature:
- Plummet volume must be calibrated (Annex A provides an example method).
- If test temperature differs significantly from calibration temperature, correct plummet volume for thermal expansion (Annex B).
- Precision:
- Repeatability (r) and reproducibility (R) are provided (examples: r ≈ 0.011 g/cm³ for coating materials with 10 cm³ plummet; R ≈ 0.030 g/cm³).
- Test report: Must include product identification, reference to ISO 2811-2:2011, plummet type/volume, test temperature, result (rounded to 0.001 g/cm³), deviations and anomalies, and date.
Applications and users
- Quality control teams in paint and varnish manufacturing for batch and production checks.
- Filling‑machine and process engineers requiring uncorrected density values for volume control.
- R&D and formulation laboratories monitoring raw materials and finished product density.
- Third‑party testing labs performing standardized density measurements for compliance or supplier verification.
Related standards
- ISO 2811 (series) - other parts cover pyknometer, oscillation and pressure cup methods.
- ISO 1513 - sample examination and preparation.
- ISO 15528 - sampling of paints, varnishes and raw materials.
Keywords: ISO 2811-2:2011, density determination, plummet method, paints and varnishes, immersed body, Archimedes’ principle, production control, calibration, temperature control, analytical balance.