4.1 A specimen of the sample is cooled under specified
conditions and, at intervals of 1°C, is drawn into a pipet under
a controlled vacuum through a standardized wire mesh filter.
The procedure is repeated, as the specimen continues to cool,
for each 1°C below the first test temperature. Testing is
continued until the amount of wax crystals that have separated
out of solution is sufficient to stop or slow down the flow so
that the time taken to fill the pipet exceeds 60 s or the fuel fails
to return completely to the test jar before the fuel has cooled by
a further 1°C.