3.1 A coating of terne metal on iron or steel articles is intended to provide drawability, solderability, or corrosion resistance, or combination thereof, which can require different amounts of coating. Specifications for terne-coated sheets frequently provide for these different classes (weights) of coating so that purchasers can select that most suitable for their needs. This test method provides a means of determining the weight of coating for comparison with the material specification requirements.

1.1 This test method covers the determination of the weight and composition of coating on terne sheet by the triple-spot method. The following three procedures are described:

1.2 If the percent of tin in the coating is required, stripping with hydrobromic acid-bromine is the preferred procedure. Steel with a predeposited electrolytic nickel coating requires a two-stage stripping method to determine total tin content. If both the tin and lead percentage are required, stripping with sulfuric acid is recommended, but caution is advised since the sulfuric acid procedure has been found to produce high tin results (see Section 11).

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazards statements, see Section 5, Note 2, and Section 17.