Corrosiveness to copper from petroleum products by Copper Strip test
12. Interpretation of Results
12.1 Interpret the corrosiveness of the sample in accordance with one of the classifications of the ASTM Copper Strip Corrosion Standard as listed in Table 1.
12.1.1 When a strip is in the obvious transition state between that indicated by any two adjacent standard strips, rate the sample at the more tarnished classification. Should a strip appear to have a darker orange color than Standard Strip 1b, consider the observed strip as still belonging in Classification 1; however, if any evidence of red color is observed, the observed strip belongs in Classification 2.
12.1.2 A 2a strip can be mistaken for a 3a strip if the brassy underlay of the 3a strip is completely masked by a magenta overtone. To distinguish, immerse the strip in wash solvent; a 2a strip will appear as a 1b strip, while a 3a strip will not change.
12.1.3 To distinguish a 2c strip from a 3b strip, place a test strip in a 25-mm by 150-mm test tube and bring to a temperature of 340 more or less 30°C in 4 to 6 min with the tube lying on a hot plate. Adjust to temperature by observing a high distillation thermometer inserted into a second test tube. Thus, a 2c strip will assume the color of a 2d strip and successive stages of tarnish; a 3b strip will take on the appearance of a 4a strip.
12.1.4 Repeat the test if blemishes due to fingerprints are observed, or due to spots from any particles or water droplets that may have touched the test strip during the digestion period.
12.1.5 Repeat the test also if the sharp edges along the flat faces of the strip appear to be in a classification higher than the greater portion of the strip; in this case, it is likely that the edges were burnished during preparation (polishing).
