"GB/T 18570.12-2008 Test for assessment of surface cleanliness of steel surface preparation before coating, Part 12: Field titration method for determination of water-soluble iron ions" specifies the field titration method for determination of water-soluble iron ions on the surface of steel before coating. This method is suitable for evaluating the cleanliness of steel surface preparation before and after, especially the content of iron ions in surface impurities. The standard is equivalent to ISO 8502-12:2003, which is easy to operate and suitable for non-professional use. It can meet most field testing needs. The standard is centralized by China Shipbuilding Industry Group company. It was issued on April 1, 2008 and implemented on September 1, 2008.