Comment on A.J. Biggin et al., A comparison of a quasi-perpendicular method of absolute palaeointensity determination with other thermal and microwave techniques, Earth and Planetary Science Letters 257 (2007) 564–581

While Biggin et al.'s paper is an important review and critique of palaeomagnetic methods employed at present, we point out here that if the grain size selectivity of microwaves is employed, instead of just using them to heat the sample, alteration can be avoided completely, and previously unavailable grain size dependence of the magnetic moment can be recovered.