This test method covers a procedure to measure a carbon black structure property by Void Volume at mean pressure. Compressed void volumes are obtained by measuring the compressed volume of a weighed sample in a cylindrical chamber as a function of pressure exerted by a movable piston. A profile of void volume as a function of pressure provides a means to assess carbon black structure at varying levels of density and aggregate reduction. For the purposes of standardized testing a single value of void volume is reported at 50 MPa mean pressure.