The influence of paste density and curing temperature on soaking and formation was investigated by different analytical methods including X-ray, porosimetry, BET and SEM. The soaking was carried out in sulfuric acid with different gravity and the time was varied between 0.5 and 24 h. Plates cured at high temperature resulting in mainly tetrabasic lead sulfate (4BS) behave markedly different to those cured at low temperature having only tribasic lead sulfate (3BS). The behaviour of plates cured at medium temperature resulting in a mix of both 4BS and 3BS was between the two extremes. There was also some influence of the paste density but smaller than the effect of different curing conditions. The results can be explained by considering the different mass structure and pore size distribution of the respective plate version.