Hard water solutions
Water solutions with different hardness have been tested. We started with purified water (PW) for technical uses (Grade 3, conf. ISO 3696), which is commonly used in ironing to prevent the formation of calcium WP 1130 and in electrical batteries. Water solutions at different hardness have been prepared by dissolving salts of calcium and magnesium hydrates in PW at different concentrations, as summarized in Table 1.