During recent years, in parallel with developments in high-speed casting, there have been increasing demands for improved steel quality. These demands are bring met by advances in our knowledge of the chemical, physical and thermal interactions between steel, gas, slag and refractory phases which take place within individual reactors as well as during transfer operations. Transfer operations must be precisely controlled, otherwise they become destroyers of quality, and quality achieved within one reactor can be lost during transfer to the next. (C) 2000 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.