ASTM D1465 Standard Test Method for Blocking and Picking Points of Petroleum Wax
12. Calculation and Report
12.1 Plot the temperature gradient curve for the instrument from the temperature recorder readings. Aside from a slight rise in temperature when the specimens are first placed on the plate, the temperature of any single point should not vary more than 0.3 °C (0.5 °F).
12.2 Measure the distance from the fold to the two blocking point marks for each specimen with the wax sample being tested. Note the blocking temperatures on the temperature gradient curve corresponding to these distances.
12.3 Report the average results to the nearest 0.5 °C (1 °F). A wax with a 41 °C (106 °F) initial film disruption and a 50 % blocking point of 43 °C (110 °F) would be reported as:
12.3.1 Picking Point - 41 °C (106 °F).
12.3.2 Blocking Point - 43 °C (110 °F).
13. Precision and Bias
13.1 Precision - Results should not differ from the mean by more than the following amounts:
13.1.1 Picking Point:
13.1.1.1 Repeatability (one operator and apparatus), 2.8 °C (5 °F).
13.1.1.2 Reproducibility (different operators and apparatus), 3.6 °C (6.5 °F).
13.1.2 Blocking Point:
13.1.2.1 Repeatability (one operator and apparatus), 1.7 °C (3 °F).
13.1.2.2 Reproducibility (different operators and apparatus), 3.3 °C (6 °F).
NOTE 4 - The precision as stated in Section 13 was obtained by a cooperative program among seven laboratories using two standard reference waxes which have sharp blocking points. Where a sharp blocking point cannot be obtained because of the composition of the wax sample being tested, poorer precision in test results will be encountered.
13.2 Bias - The procedure in this test method has no bias because the measurement of blocking and picking points can be defined only in terms of a test method.
14. Keywords
14.1 blocking point; picking point; waxed coating; waxed paper
