Apiezon® wax W is a low vapour pressure wax for sealing joints in high vacuum systems. This wax softens at 80-90°C and has a vapour pressure at 80°C of 10-3 mbar and at 20°C of 10-8 mbar.
Apiezon® wax W40 is similar to type W but has a lower softening point which makes it very suitable for flow sealing in or around vacuum joints. It is not recommended for use at temperatures above 30°C. It has a vapour pressure at 20°C of 10-7 mbar.