Overview
ISO 16925:2021 specifies a test method to evaluate the resistance of paints and varnishes to pressure water-jetting. The standard simulates the mechanical effects of a high-pressure water jet on a coated substrate and defines the apparatus, specimen preparation, test procedures and a visual evaluation system. It is intended for reproducible assessment of coating degradation (peeling, flaking or loss of adhesion) caused by water-jet impact.
Key topics and requirements
- Scope & principle: Measures loss of adhesive strength and damage caused by a defined pressure water-jet; results are judged by visual comparison to reference illustrations.
- Apparatus: High-pressure pump and nozzle with adjustable pressure, mass flow rate and water temperature. Recommended capability: mass flow 8–14 kg/min, pressure 4–13 MPa (40–130 bar), temperature 20–80 °C. Nozzle angle, fixing and flow calming are required for reproducibility.
- Calibration: Annex A details calibration and mass flow rate adjustment (nozzle with 40° jet angle and 6 kg/min at 2 MPa referenced for adjustment).
- Specimen preparation: Sampling and preparation per ISO 15528 and ISO 1513; dry film thickness measured according to ISO 2808. Conditioning: 48 h at 60 °C or 7 days at room temperature (cool to RT before scribing if conditioned at 60 °C).
- Cutting / scribing: Introduce straight-line cuts/scribes through the coating into the substrate (St Andrew’s cross arrangement). Tools: cutter knife (“C”), van Laar (“L”) or Sikkens (“S”) per ISO 17872.
- Test methods: Three preferred methods (A, B, C) with defined parameters:
- Water temperature 60 ± 2 °C; impact angle 90° ± 2°
- Nozzle–sample spacing: 100 mm (methods A, B) or 130 mm (method C)
- Mass flow rate: 11.3 ± 0.2 kg/min; durations: 30 s (A) or 60 s (B and C)
- Evaluation: Visual comparison to illustrations gives a characteristic value 0–5 indicating degree of damage; report should identify main separation plane (e.g., substrate/primer).
Applications and users
ISO 16925 is used by:
- Coating manufacturers (R&D and quality control) to validate formulation resistance to water-jet erosion
- Independent test laboratories for specification compliance and certification
- Asset owners, contractors and inspectors in industries where high-pressure cleaning or jetting is used (marine, shipbuilding, offshore, infrastructure, industrial maintenance)
- Specifiers and procurement teams writing performance requirements for protective coatings
Keywords: ISO 16925, pressure water-jetting, coating resistance, paints and varnishes, test method, high-pressure water jet, mass flow rate, film thickness, scribing
Related standards
- ISO 1513 - Examination and preparation of test samples
- ISO 2808 - Determination of film thickness
- ISO 4618 - Terms and definitions for paints and varnishes
- ISO 15528 - Sampling
- ISO 17872 - Guidelines for introducing scribe marks through coatings
Open preview (PDF)Paints and varnishes — Determination of the resistance of coatings to pressure water-jetting