The second stage starts once the resistivity stabilises and corresponds to a temperature ramp up to the curing temperature of 160 °C. This corresponds to times between 40 and 70 min for the 15 A/m2 experiment and 30–60 min for the 45 A/m2 experiment. During this stage the resistivity of the material decreases at a relatively constant rate, goes through a minimum and then increases (Fig. 4). The curing reaction starts when the material reaches a temperature of about 135 °C; which implies that the first half of this stage is carried out with insignificant chemical changes in the epoxy resin. Thus, the changes in resistivity during this phase are dominated by the temperature increase and the drop observed can be attributed to the increase in conductivity of the liquid epoxy, as a result of the higher mobility of migrating charges with increasing temperature. Once the reaction starts – in the second half of this stage – the resistivity increases. This increase is attributed to the effect of cross linking on the viscosity of the thermosetting polymer and the corresponding effect on the mobility of migrating charges which dominates the electrical response of the resin [38].