Industrial porcelain and gelcoat samples were prepared. Two kinds of porcelain, soft and hard, have been prepared by adding the hardener with concentrations of 2.5% and 5% gm, respectively. unsaturated polyester that is reinforced with calcium carbonate (CaCO₃) with equal values. Also, a gelcoat was prepared using unsaturated polyester and silica fume (S.F.) that was added in different weight ratios (0.25, 0.5, 0.75, 1%). The mechanical and thermal properties of porcelain and gelcoat samples were studied; also, water uptake has been determined. The hardness values of soft porcelain and hard porcelain are 53 and 49, respectively, while the hardness value increased to a higher value (81.5) for selected gelcoat (UPE / 0.5% S.F). The impact strength values of soft and hard porcelain are 2.3332 kJ/m² and 2.666 kJ/m², respectively, and improved to a higher value (4.3 kJ/m²) by using gelcoat. Finally, a gelcoat improves the resistance to water diffusion for both types of porcelain after immersing in water for seven days