<p>An article is formed in a mould by blowing a parison hot plastics material with a blowing gas. A cooling fluid is introduced through either blow pin 26 or blow pin 28 into the article to cool the article and thus allow its removal from the mould. The cooling fluid is formed by mixing liquid nitrogen and relatively warm nitrogen gas in a jet pump 22. The nitrogen gas is supplied from a storage vessel 24, having been recovered from a previous cooling step. The cooling fluid flows through the article to the other of the pins 26 and 28, is withdrawn from such pin and flows to the vessel 24 for use in cooling a subsequently formed article. Valves may be provided to switch the roles of the pins 26 and 28 and thereby reverse the direction of flow in the article being cooled. <IMAGE></p>
