Overview
EN ISO 1460:2020 - "Metallic coatings - Hot dip galvanized coatings on ferrous materials - Gravimetric determination of the mass per unit area" specifies a laboratory gravimetric method to measure the mass per unit area (g/m²) of hot-dip galvanized coatings. The procedure dissolves the zinc coating in an inhibited acid stripping solution and determines coating mass from the weight loss of a sample of known exposed surface area. The standard is mainly applicable to parts whose surface area can be determined accurately.
Key topics and technical requirements
- Principle: Dissolve the zinc coating in an inhibited HCl solution and calculate coating mass from the sample weight difference before and after stripping.
- Stripping solution: Prepare by dissolving 3.5 g hexamethylenetetramine in 500 ml concentrated hydrochloric acid (ρ ≥ 1.18 g/ml) and diluting to 1 000 ml with distilled water.
- Sample preparation: Degrease with a solvent that does not attack the coating; dry prior to testing.
- Weighing accuracy: Initial and final mass must be determined to an accuracy better than 1% of the presumed coating mass.
- Solution volume: Provide at least 10 ml of stripping solution per cm² of exposed surface area; immerse at room temperature until hydrogen evolution ceases (end point).
- Surface area measurement: Surface area A must be determined to within 1% accuracy for reliable results.
- Calculation: Mass per unit area (g/m²) is obtained from the mass loss (m1 − m2) divided by the exposed area, with appropriate unit conversion (area typically measured in mm²). For steel wire, an alternative formula using wire diameter and steel density (7.84 g/cm³) is permitted.
- Uncertainty/reproducibility: Inter-laboratory reproducibility is about ±5% of the mean value.
- Reporting: Reports shall reference ISO 1460, include sample type/dimensions, method used to compute surface area, coating mass (g/m²) or agreed thickness (µm), any deviations, observations and test date.
Applications and users
- Quality control and acceptance testing of hot-dip galvanizing in fabrication and construction
- Inspection and verification for procurement and compliance with coating specifications
- Corrosion engineers, metallurgists and testing laboratories measuring coating mass for durability assessments
- Galvanizing plants and manufacturers ensuring process consistency and product certification
- Researchers comparing coating mass data and validating new processes
Related standards and notes
- Prepared by ISO/TC 107 in cooperation with CEN/TC 262; CEN adopted ISO 1460:2020 as EN ISO 1460:2020.
- This edition supersedes earlier ISO/EN versions (previously ISO 1460:1992 / EN ISO 1460:1994).
- Approximate coating thickness can be estimated from mass per unit area assuming a zinc coating density (note: ISO uses 7.2 g/cm³ for the coating in thickness approximations).
Keywords: EN ISO 1460:2020, hot dip galvanized coatings, gravimetric determination, mass per unit area, galvanizing quality control, stripping solution, hexamethylenetetramine, coating mass measurement.
