The ISO 4520-1981 "Chromate conversion films for zinc and cadmium layers of Eletroplating" standard specifies the requirements for chromate conversion films for corrosion protection on zinc and cadmium layers of Eletroplating. The standard covers the method of formation of chromate conversion films, Color type, performance criteria and their effect on platings. Chromate conversion films are formed by immersing zinc or cadmium layers of Eletroplating in a chromate solution. Appearance and performance of the film layer are affected by the composition, pH value, temperature and treatment time of the solution. The standard also specifies conditions to be avoided during drying and washing to ensure film mass and Stability. The standard does not apply to surface preparations that provide only Color or improve paints adhesion.