jats:titleAbstract</jats:title>jats:pAn innovative fluid‐dynamic gauging (FDG) device to study the initial as well as long‐term swelling or removal of soft solid layers immersed in a liquid environment in real time and in situ is presented. This sideways FDG (SiDG) device was developed for soft solid layers whose properties change significantly on contact with liquid. Calibration tests indicated a resolution of ±10 μm. The open source computational fluid dynamics (CFD) code OpenFOAM was used to model the flow in the SiDG nozzle. Good agreement was obtained between experimental and CFD results at different nozzle clearances, so that the shear stress exerted by the gauging flow can be computed accurately. A series of demonstration studies are presented, on layers of petroleum jelly, polyvinyl acetate, gelatin and a complex model soil. Initial swelling dynamics are captured and the influence of pH on initial swelling behavior, previously inaccessible, is reported.</jats:p>