While this can be accomplished by continuous metering of all the separate ingredients, the number of feeders needed and the difficulties of rapid change from one formulation to another usually render this approach impractical. A normal approach to overcome these problems is batch blending of particulate ingredients prior to feeding to the continuous mixer. Most continuous mixers require a metered feed but if a uniform and consistent blend of all the ingredients can be achieved, only one metering device is required. In addition, conventional batch weighing methods used throughout the rubber industry can be utilised to deliver ingredients to the blender.