Thermal spray coatings are widely used to give or improve a specific surface quality or function to a workpiece. Different spraying methods result in different characteristics of the coatings, and they are mainly applied for corrosion, heat and wear resistance. Metallographic examination of spray coatings includes estimation of porosity, oxides and unmelted particles as well as adhesion to the substrate. Because incorrect grinding and polishing procedures can influence the evaluation of the true porosity it is very important that metallographic preparation is carried out systematically and that the results are reproducible. Precision cutting with the correct cut-off wheel is recommended to avoid cracks in the coating. Mounting should follow with slow curing epoxy. Coarse grinding introduces the most damage to the coating and should therefore be carried out with the fi nest grit possible. To avoid relief fi ne grinding with diamond on a rigid disc is recommended, followed by a thorough diamond polish on a silk cloth. It is particularly important to be aware that metal coatings behave differently to ceramic coatings under mechanical abrasion and that the diamond polish needs to be long enough to reveal the true porosity. The recommended preparation procedure is based on experience and gives excellent results for the majority of common thermal spray coatings. However, it should be noted that for some specific proprietary coatings the polishing times may need to be adjusted.