Temperature-Controlled Bath—Use a transparent liquidbath of sufficient depth such, that at no time during themeasurement of flow time, any portion of the sample in theviscometer is less than 20 mm below the surface of the bathliquid or less than 20 mm above the bottom of the bath.6.3.1 Temperature Control—For each series of flow timemeasurements, the temperature control of the bath liquid shallbe such that within the range from 15 °C to 100 °C, thetemperature of the bath medium does not vary by more than60.02 °C of the selected temperature over the length of theviscometer, or between the position of each viscometer, or atthe location of the thermometer. For temperatures outside thisrange, the deviation from the desired temperature must notexceed 60.05 °C