Carbon black is added to elastomers as a reinforcing agent to significantly enhance certain properties. It is measured by heating a weighed sample in a combustion boat at 850° C under a stream of nitrogen. The combustion boat containing the sample is cooled and weighed again. The carbon black is then burned off in an air atmosphere and the combustion boat is weighed again. The loss in mass represents the amount of carbon black. The type of carbon black used in the formulation can be determined using electron microscopy.