Liquid processable, nanometer-scale polymer coatings are integral to many technical applications. The solvent mass transport parameters are often unknown, yet they are crucial for determining drying time, residual solvent content, long-term stability, and layer mixing. By establishing a measurement technique and conducting experimental and numerical investigations, the different mass transport behavior in polymer films during the transition from micro- to nanolayers is demonstrated. Solution-casted polymer nanolayers play a significant role in various technical applications. The solvent mass transport parameters, while frequently unknown, are a decisive factor in determining drying times, trace solvent amounts, long-term stability, and multilayer intermixing. Through the development of a measurement system and comprehensive investigations, the differences in mass transport characteristics are explored.