ASTM D3944 Test Method for Solidification Point of Petroleum Wax
7. Procedure
7.1 Calibrate the recorder at least every 60 days when in frequent use (see Annex A1).
7.2 Obtain a wax sample representative of the material to be tested.
7.3 Using a balance accurate to at least 1 mg, weight 50 + 5 mg of sample by putting a few tiny pieces of solid wax into a tared 6 by 50-mm test tube.
7.4 Start the temperature recorder. A horizontal pen speed of about 150 mm (5 in.)/10 min for a X-Y recorder or a chart speed of about 150 mm (5 in.)/10 min for a strip chart recorder is usually appropriate.
7.5 Heat the sample by any convenient method, such as by use of:
7.5.1 A hot air blower.
7.5.2 An aluminum heating block.
7.6 When using any method of heating a sample, note that the wax absorbs heat slowly. Hence caution must be used not to overheat the surface near the heating medium. Overheated wax can degrade. A minute amount of degradation affects results.
7.7 When the sample melts, insert the thermocouple probe into the melted wax.
7.8 Let the wax sample temperature rise 10 to 15°C above the expected solidification point.
7.9 Transfer the 6 by 50-mm test tube, together with its heated specimen, from the heating medium to a 25 by 52-mm vial which acts as a cooling chamber (See Fig. 1).
7.10 Let the specimen cool until the curve traced by the cooling wax on the recorder chart paper levels off.
7.11 Determine the point in the curve which shows the first significant change in the slope of the curve (see Fig. 3). This is the solidification point.