This part of ISO 5794 specifies the test formulation, equipment, procedure, and test methods for determining the physical properties of precipitated hydrated silica in a styrene-butadiene rubber mix. ISO 5794-1 describes methods for chemical analysis of precipitated hydrated silica, describes its physical and chemical properties, and classifies silica with respect to their specific surface area obtained by nitrogen adsorption. ISO 5794-3 specifies the test formulation, equipment, procedure, and test methods for determining the physical properties of precipitated hydrated silica in a compound based on a blend of solution styrene-butadiene rubber and butadiene rubber.