This International Standard specifies a method for the determination of the particle size distribution (less than 60 μm) of aluminium oxide primarily used for the production of aluminium, using electroformed sieves. NOTE — There is no correlation, for the calcined alumina, between the results obtained with the square-aperture and the round-aperture electroformed sieves. The use of either kind of sieve should be clearly indicated in the compilation of the test report, as well as in the agreement protocols between suppliers and purchasers if the particle size distribution is indicated in the contract.