ASTM D127 Method for Drop Melting Point of Petroleum Wax including Petrolatum
7. Procedure
7.1 Secure a sample of sufficient size that is representative of the material under inspection. Use a fresh portion of the sample for each set of two determinations. Melt the sample slowly until the temperature reaches 93°C (200°F), or about 11°C (20°F) above the expected drop melting point, whichever is higher. Place sufficient sample in a flat bottom container to give a sample depth of 12 more or less 1 mm. Adjust the temperature of the sample to 6 to 11°C (10 to 20°F) (Note 2) above its drop melting point using any general laboratory thermometer for measurement. Chill one of the test thermometer bulbs to 4°C (40°F). Wipe dry, and, quickly but carefully, immerse the chilled bulb vertically into the heated sample until it touches the bottom of the container (12 mm submerged) and withdraw it immediately. Hold the thermometer vertically away from the heat until the surface dulls, and then place it for 5 min in water having a temperature of 16°C (60°F). Prepare another specimen from the same sample using this procedure.
NOTE 2 - A dipping temperature of 11°C (20°F) above the congealing point in accordance with Test Method D938 usually will be 6 to 11°C (10 to 20°F) above the actual drop melting point.
7.2 Securely fix the thermometers in the test tubes by means of corks so that the tip of each thermometer is 15 mm above the bottom of its test tube. Insert the test tubes in the water bath which is at 16°C (60°F) and adjust the height of the test tubes so that the immersion marks on the thermometers are level with the top surface of the water. Raise the temperature of the bath at a rate of (3°F) 1.7°C/min to 38°C (100°F) , then at a rate of 1°C (2°F)/min until the first drop of material leaves each thermometer. Record in each case the temperature at which the first drop falls from the thermometer.
