The client observed that the enamel coatings of their bathtubs were not smooth. They employed ITL to classify the deposits in the coatings and determine their source.
Initially, the samples were analyzed using planar SEM, but since the deposits were between two of the enamel layers, cross-sectional SEM was required. Foreign inclusions were discovered along a crack that ran parallel to the surface. EDS analysis of the enamel away from the crack, and of the white deposits within the crack revealed that the deposits contained increased amounts of iron and calcium. In the second sample, SEM revealed that the remnants of a fly or small bug were trapped about 100 µm from the interface of the prime coating and the base metal.
The two primary causes of the enamel roughness were cracking and small insects adhering to the surface.
By screening a window near the enamel coating process, further contamination by insects was prevented.