Irregular surface structures, commonly referred to as “roughness”, such as those found on grey cast iron or sand-blasted steel, complicate the thickness measurement of overlying paint layers. The uneven substrate surface can cause large fluctuations in the measured values, leading to uncertainties in the interpretation of the results and making it difficult to monitor the coating process.

The underlying surface roughness always influences an overlying paint layer. However, it is challenging to make a quantitative assessment of the degree of interference as it depends on several parameters, such as the geometry of the roughness and the thickness of the lacquer. When measuring with a single-poled probe, measurement positions over roughness peaks or valleys may lead to different readings despite uniform paint thickness.

In this Application Note you will learn, among other things:

• which device-probe- combination is suitable for this measuring task.
• comparative measurements between a standard probe and the FISCHER solution for this measuring task.