Magnetic minerals in rocks record the direction and intensity of the ambient magnetic field during formation, providing, for example, varied information of the geomagnetic field and past tectonic plate motions. In order to reliably interpret palaeomagnetic measurements, the mechanisms that induce magnetic remanence and those that can subsequently alter it must be fully understood. Whilst some mechanisms, such as thermoremanent magnetisation (TRM) acquisition, are broadly understood, there is also a wide class of mechanisms that come under the heading of chemical remanent magnetisation (CRM) that require further study. Currently, models of CRM processes only exist for the smallest, uniformly magnetised grains, termed single domain (SD). However, the magnetic signal from rocks is often dominated by slightly larger grains containing non-uniform magnetisation states and these are termed pseudo-SD (PSD) grains. The latest advanced transmission electron microscopy (TEM) techniques like electron holography and environmental TEM allows for the imaging of magnetisation on nanometre scales as minerals alter during in situ heating under controlled oxidising/reducing atmospheres. In this context, a suite of complementary techniques used to examine local changes in magnetisation of synthetic PSD magnetic recorders as they undergo in situ chemical alteration within the TEM is presented.