Continuous casting mould-powder (also known as 'mould-flux') is used primarily to facilitate passage of cast through water-cooled mould. On spraying at the top of hot metal surface in the mould region, it melts at a defmite rate and forms a molten glassy slag, which passes through the interface of mould and steel strand as a thin film, thus acting as a lubricant between these two faces. Besides this, the.powder also serves as a thermal insulator and removes simultaneously the inorganic inclusions (mostly alumina). Mould powders are manufactured using a number of inorganic raw materials and it has been found that no universal formula can be worked out which performs equally well for all steel plants under different casting conditions and grades of steel. Hence, it is important to know the property - composition relationship of a mould powder so as to select the right material suitable for a particular set of casting conditions and which, in tum, will help the shop-floor personnel in altering the powder composition according to their plant running parameters.