Overview
EN ISO 2178:2016 - "Non‑magnetic coatings on magnetic substrates - Measurement of coating thickness - Magnetic method" - specifies a non‑destructive, tactile method for measuring the thickness of non‑magnetizable coatings (e.g., paints, varnishes, electroplated layers, enamels, plastics, powder coatings, claddings) applied to magnetizable base metals. Measurements are made by placing a magnetic probe (or instrument with an integrated probe) directly on the coating; the coating thickness is displayed by the coating thickness gauge. The standard also notes applicability to the reverse case (magnetizable coatings on non‑magnetizable bases - see ISO 2361).
Key topics and technical requirements
- Measurement principles: Describes magnetic measurement techniques including the magnetic pull‑off method, magnetic inductive principle and magnetic flux gauges.
- Tactile, non‑destructive testing: Probe contact measurement intended for typical coatings where the substrate is magnetizable.
- Factors affecting accuracy: Detailed coverage of influences such as:
- magnetic properties of the base metal,
- electrical properties of coating materials,
- base metal thickness and geometry (edge and curvature effects),
- surface roughness and cleanliness (lift‑off),
- probe pressure and tilt,
- temperature and external electromagnetic fields.
- Calibration and adjustment: Requirements for instrument calibration, use of thickness reference standards and methods for adjustment of coating thickness gauges.
- Measurement procedure & evaluation: Guidance on number of measurements, sampling, data evaluation and reporting.
- Uncertainty & precision: Methods for estimating measurement uncertainty (combined and expanded) and precision metrics (repeatability and reproducibility limits).
- Documentation: Items to include in a test report and informative annexes with examples and uncertainty estimation approaches.
Applications and who uses it
EN ISO 2178:2016 is widely used for quality control, inspection and asset maintenance where coating thickness is critical:
- Coating inspectors and QA/QC engineers in automotive, aerospace, marine and general metal finishing.
- Surface treatment and plating shops verifying non‑magnetic coating deposits.
- Maintenance teams checking protective coatings for corrosion protection.
- Calibration laboratories and test houses assessing instrument performance and uncertainty.
- Coating manufacturers and specification authors seeking standardized thickness measurement methods.
Keywords: EN ISO 2178:2016, coating thickness measurement, magnetic method, non‑destructive testing, coating thickness gauge, non‑magnetic coatings, magnetizable base metals, calibration, measurement uncertainty.
Related standards
- ISO 2361 (measurement of magnetizable coatings on non‑magnetizable substrates)
- ISO 2064 (definitions and conventions for coating thickness)
- ISO 4618 (paints and varnishes - terms and definitions)
- ISO 5725‑1 and ISO/IEC Guide 98‑3 (accuracy and uncertainty of measurement)
