This International Standard specifies gravimetric methods for determining the coating mass per unit area of conversion coatings on metallic materials. The methods are applicable to — phosphate coatings on iron and steel; — phosphate coatings on zinc and cadmium; — phosphate coatings on aluminium and its alloys; — chromate coatings on zinc and cadmium; — chromate coatings on aluminium and its alloys. The methods are applicable only to conversion coatings that are free from any supplementary coating such as oil, water or solvent-based polymers, or wax. The methods do not indicate the presence of bare spots or sites with thicknesses lower than the specified minimum in the measuring areas. In addition, the single values obtained from each measuring area is the mean thicknesses over that area. There can be no further mathematical analysis of this single value, e.g. for statistical control purposes.