The ASTM B556-90 (2023) standard provides a speckle test method for the measurement of electrodeposited chromium Coating thickness on nickel and stainless steel. The method is suitable for chromium coatings up to a thickness of 1.2 μm with a Measurement accuracy of approximately +/- 20%. This test method is particularly suitable for cases where chromium Coating thickness is thin and assumes that muriatic acid dissolves chromium at a consistent rate under specific conditions. Although the method can be used for approximate determination, for coatings thicker than 0.5 μm, double drop acid is recommended to avoid test solution depletion.