number of pyrometers 20 at the top of receptacle 18 where the droplets 28 are collected measure the temperature of the droplets 28 and the gas velocity is adjusted to ensure that the temperature of droplets 28 is with predetermined limits for example if the droplets have not cooled sufficiently the gas velocity is increased to slow the droplets further to increase the radiation heat loss a rolling temperature much higher than the conventional one is practicable because in the absence of oxygen there is no risk of 34 burning 34 of the steel the upper limit of the rolling temperature may approach the lower limit of solidification of the steel being processed provided that the rolled product 30 has enough strength and stiffness for further processing as it leaves the reduction rolls 21 the required level of collected droplets 28 in the receptacle is maintained by automatic speed control of rolls 21 by a level control instrument 19 near the top of receptacle 18 and a connected servo mechanism not shown the steel is not to be contaminated by oxides and therefore no air vapour or gas other than the inert cooling gas must come into contact with the steel during processing i e between pouring and the point the steel.