Measuring coating layer shape in arbitrary geometry

Coating processes are typically analyzed on systems with flat substrates, such as the Landau–Levich–Derjaguin configuration in dip coating. However, actual applications often exhibit a much wider variety of geometries. For example, dip coating is also employed as a batch process with three-dimensional substrates. After the batch dip coating process, the coating layer is likely to exhibit irregular geometries near the lower edge of the substrate; the substrate profile is not flat, and the fluid can form overhangs depending on process conditions and rheological properties. These irregularities make it impossible to define layer shape measures, such as average thickness and roughness, in traditional ways. In this study, we propose generalized measures to overcome this issue by using offset distance and curve similarity. Our measures can quantify the shape of the coating layers in arbitrary …