ISO 1407:2009 specifies three methods for the quantitative determination of the material extractable from raw rubbers, both natural and synthetic, and their unvulcanized and vulcanized compounds.
method A measures the mass of the solvent extract, after evaporation of the solvent, relative to the mass of the original test portion;
method B measures the difference in the mass of the test portion before and after extraction;
method C, which is for raw rubber only, measures the difference in the mass of the test portion before and after extraction using boiling solvent.
Recommendations as to the solvent most appropriate to each type of rubber are given in an annex.