The spontaneous dewetting of a liquid film from a solid surface occurs in many important processes, such as printing and microscale patterning. Experience suggests that dewetting occurs faster on surfaces of higher film repellency. Here, we show how, unexpectedly, a surrounding viscous phase can switch the overall dewetting speed so that films retract slower with increasing surface repellency. We present experiments and a hydrodynamic theory covering five decades of the viscosity ratio between the film and the surrounding phase. The timescale of dewetting is controlled by the geometry of the liquid-liquid interface close to the contact line and the viscosity ratio. At small viscosity ratio, dewetting is slower on low film-repellency surfaces due to a high dissipation at the edge of the receding film. This situation is reversed at high viscosity ratios, leading to a slower dewetting on high film-repellency surfaces due to the increased dissipation of the advancing surrounding phase.

液膜从固体表面自然脱湿发生在许多重要过程中，例如印刷和微缩图案化。经验表明，在具有较高膜排斥性的表面上反润湿发生得更快。在这里，我们展示了出乎意料的是，周围的粘性相如何改变整体的去湿速度，从而使膜随着表面排斥性的增加而收缩得更慢。我们提出了实验和流体力学理论，涵盖了薄膜与周围相之间的五十年粘度比。去湿的时间尺度由靠近接触线的液-液界面的几何形状和粘度比控制。在低粘度比的情况下，由于在后退膜边缘的高耗散性，在低膜排斥性表面上的去湿较慢。