Abstract: A method of and apparatus for evacuating a chamber, for example in vacuum glazing, that is enclosed in part by a glass wall that includes an evacuation port. An evacuating head is employed and is arranged to cover the port and a portion of the glass wall that surrounds the port. The evacuating head has a first cavity that communicates with the port and at least one further cavity that surrounds the first cavity. The first and further cavities are connected by conduits to respective vacuum pumps, which apply differential negative pressure to the first and further cavities, and the chamber is evacuated by way of the first cavity. Evacuation of the chamber may be effected whilst the glazing is subjected to high temperature out-gassing.