| A section of a sample unit not less than 300 mm long shall be kept for 12 hours in a dry atmosphere at a temperature of 65 °C ± 2 °C, after which the sample shall be allowed to cool for 1 hour at 23 °C ± 2 °C. It shall then be kept for 12 hours at a temperature of - 20 °C ± 2 °C. | a0c0 |