Atomic Force Microscopy (AFM) was an unusual but effective tool used to investigate the morphology of cured blends based on UP (unsaturated polyester). The pertinence of AFM was evaluated by studying four miscible UP/LPA (low profile additive)/ST (styrene) blend systems. The morphology of these cured blends before and after LPA solubilization was analogous in SEM (Scanning Electron Microscopy) and AFM. However, in AFM the particles boundaries were more defined compared to SEM. Before treatment, nanoparticles (less than 60 nm) and aggregates (140 to 250 nm) were discernible. After treatment, nanogels (less than 50 nm) and microgels (80 to 220 nm) were observed. The aggregates composed of linked nanoparticles, were connected together to form a whole network. The microgels were composed of linked nanogels and were connected to form a polyester network. The LPA solubilization reduced the nanoparticles to nanogels in extracting the LPA phase out of the nanoparticles. The particles size depended on the miscibility of the system UP/LPA/ST and was related to the void volume. Shrinkage and light opacity were macroscopic properties which characterized the void volume and therefore the particle sizes.