ASTM D4287 test method for high-shear viscosity using a cone/plate viscometer
9. Procedure
9.1 With the cone in the down position (in contact with the plate), turn the instrument on and allow it to warm up for at least 5 min. For a multitemperature instrument, set at 25°C or to an alternatively agreed upon temperature. Raise the cone to the up position. Transfer a suitable amount of the product to be tested to the plate, taking care to avoid the inclusion of air bubbles, and again lower the cone to the down position. Wait for 30 s to allow the specimen to attain the agreed upon temperature.
9.2 Start the cone rotating and record the reading o. When using an analog viscometer, record the reading when the point becomes steady (Note 4). When using a digital viscometer, record the reading directly from the digital display once it has been stabilized (Note 5).
NOTE 4 - With an analog cone/plate viscometer, whether the reading gives a direct indication of the viscosity or not, depends on the cone and scale used.
NOTE 5 - In some cases it is difficult to judge whether a constant reading has been obtained. However, if the reading does not become steady after 15 s, record the reading at 15 s and mention the lack of a constant reading in the test report. If highly accurate readings are required, make the readings below 90 % of the scale.
9.3 If the reading does not directly indicate the viscosity, multiply the reading by the appropriate conversion factor or use the appropriate calibration curve to obtain the viscosity.
9.4 Clean both the cone and the plate carefully, employing a cloth or tissue and a suitable solvent. Take care to remove all of the test material and cleaning solvent. Do not use cleaning utensils that may damage the apparatus. Metal cleaning tools must never be used.
9.5 Repeat the determination with a second specimen. If the two viscosity determinations differ by less than 7 %, calculate their mean and report as the high-shear viscosity for the material. If they differ by more than 7 %, make a third determination. If no two readings are within 7 % of each other, then the material is not suitable for testing by this test method.
