This International Standard specifies two methods for the determination of ash from raw rubbers, compounded rubbers and vulcanizates. The methods are applicable to raw, compounded or vulcanized rubbers of the M, N, O, R and U families described in ISO 1629, except that: — Method A shall not be used for the determination of ash from compounded or vulcanized rubbers containing chlorine, bromine or iodine. — Method B shall be used for compounded or vulcanized rubbers containing chlorine, bromine or iodine. lt shall not be used for uncompounded rubbers. — Lithium and fluorine compounds may react with silica crucibles to form volatile compounds, giving low ash results. Platinum crucibles shall therefore be used for ashing fluorine-containing and Iithium-polymerized rubbers. This International Standard does not cover the interpretation of the ash results as to the inorganic chemical content of a compound or vulcanizate. This is the responsibility of the analyst, who has to be aware of the behaviour of rubber additives at elevated temperatures. The two methods of ashing do not give identical results in all cases, and it is necessary to state in the test report the method of ashing employed.