The most frequent defects on painted parts are craters, pimples and blisters as well as adhesion problems. Such defects can occur during injection moulding or painting or any transportation or handling step in between. Adhesion problems can usually be easily identified by means of climate change tests or cross-hatch adhesion tests. Craters can be characterized by way of simple, light microscopic analyses.The identification of pimples and blisters and their origin requires more elaborate microscopic and analytical investigations. Another frequently occurring defect is the formation of crack after painting.