Method of tempering a molding tool

A method of tempering a molding tool comprising (a) introducing molten polymer into a molding cavity, said molding cavity formed by at least two members, wherein at least one of said molding members is made of sintered metal or metal alloy having communicating pores, the pores being closed toward said molding cavity;

• (b) introducing a coolant fluid at higher than atmospheric pressure into said communicating pores, of said porous molding member, said fluid selected from the group consisting of carbon dioxide, nitrogen, air, argon, helium, hydrogen or a mixture of at least two thereof and introduced into said pores by means of at least one inlet which passes through an envelope surface being tight at least around said inlet, the coolant fluid being evacuated via at least one separate evacuation channel or via open parts of the envelope surface, whereby said molten polymer is solidified into a polymeric article in said molding cavity by said coolant fluid;
• and (c) opening said molding tool.