Overview
ISO 1522:2022 - "Paints and varnishes - Pendulum damping test" specifies two standardized methods for measuring the damping (decay) of a pendulum oscillation in contact with a coated surface. The test quantifies the viscoelastic response of paint, varnish or related coating systems (single or multicoat) and is commonly used as an indicator of surface softness / hardness. ISO 1522 covers instrument design, calibration, sample preparation, test procedure, expression of results and precision data.
Key topics and requirements
- Two pendulum methods: the König pendulum and the Persoz pendulum, each defined by geometry, mass and oscillation characteristics. They differ in ball diameter (König Ø5 mm, Persoz Ø8 mm), period (≈1.40 s vs ≈1.00 s) and reference damping intervals (König: 6° → 3°, Persoz: 12° → 4°).
- Calibration and verification: normative calibration procedures are included (Annex A for König, Annex B for Persoz), including checks for deformation and reference damping on polished float glass.
- Sampling and panel preparation: sampling per ISO 15528; sample preparation and test panels follow ISO 1513 and ISO 1514. Panels should be flat, rigid and typically ~100 × 100 × 5 mm.
- Conditioning and ambient conditions: tests are performed under controlled laboratory conditions, normally (23 ± 2) °C and (50 ± 5) % relative humidity, with minimum panel conditioning for 16 h.
- Film thickness: dry-film thickness is measured per ISO 2808; a minimum preference of ~30 µm dry film is recommended for reliable results.
- Procedure and measurement: three measurements on different panel areas; time for amplitude decay is recorded (manual or automatic timing). Results depend on film thickness, substrate and environmental conditions.
- Precision and comparability: precision statements are provided for both pendulums. Important: results from König and Persoz are not directly interchangeable - use a single pendulum type for a measurement series.
Applications and users
- Quality control and production testing of coatings to monitor surface hardness/softness.
- R&D and formulation development for paints, varnishes, protective coatings and multilayer systems.
- Comparative testing between formulations or curing regimes.
- Failure analysis and contract specification verification in industries such as automotive, marine, industrial coatings and flooring.
- Typical users: coating manufacturers, independent test laboratories, specification writers, and quality engineers.
Related standards
- ISO 1513 - Examination and preparation of test samples
- ISO 1514 - Standard panels for testing
- ISO 2808 - Determination of film thickness
- ISO 4618 - Terms and definitions for paints and varnishes
- ISO 15528 - Sampling of paints and varnishes
Keywords: ISO 1522, pendulum damping test, paints and varnishes, König pendulum, Persoz pendulum, coating hardness, test panels, calibration, dry-film thickness, ambient conditions.