ASTM D4048 test method for detection of copper corrosion from lubricating grease
11. Report
11.1 Report the corrosiveness in accordance with one of the classifications and descriptions in Table 1. State the duration of the test and the test temperature.
12. Precision and Bias
12.1 Due to the nature of the results, the precision of this test method was not obtained in accordance with RR: D02-1007.
12.1.1 Repeatability - can be judged by the fact that 96 % of duplicate results obtained in the normal simultaneous procedure by twelve laboratories with six samples were in agreement (see Note 3).
12.1.2 Reproducibility - may be judged by the fact that twelve laboratories matched consensus within a numerical classification (1, 2, 3, 4) 92 % of the time and within a numerical and descriptive classification (a, b, c, d) 69 % of the time with five samples showing good or poor protection against copper corrosion. A sample (Grease F) with somewhat marginal corrosion protection properties found agreement between laboratories only 50 % of the time by either numerical or numerical and descriptive classification.
NOTE 3 - Actual data on which this precision statement is based can be found in Appendix X1. Test conditions were 100°C, 24 h.
12.2 Bias - The procedure in Test Method D4048 has no bias because the rating of copper corrosion is defined only in terms of this test method.
13. Keywords
13.1 copper corrosion; copper strip; copper tarnish; lubricating grease
